1 2 3 Previous 231 Replies Latest reply on Sep 25, 2012 5:22 AM by Roger Wolff

    RG1 1.8v regulator

      Ok, so in a different thread I threatened to remove RG1 and do some current measurements on it's output after seeing those thermal images that show it's not generating any heat...

       

      Well, I did it tonight. Some photos here: https://picasaweb.google.com/selsinork/RPi18v

       

      The jumper pins in the output let me either just put a jumper on and verify the Pi boots ok, or wire a multimeter in series to get some current readings.

       

      The results were interesting to say the least. I had to go back and check I was reading the multimeter correctly, that it wasn't broken etc.

       

      On initial power up I see a negative current for a second or so which then reverses to about 0.5mA (yes half a milliamp, that's not a typo) for a few seconds while we get the first sd-card accesses. Once we're booted and sitting at the login prompt the current reading fluctuates from around 0.001mA to maybe 0.04mA. 

       

      I'm using the 40mA range on a decent Fluke multimeter, so I've no reason to doubt the results. There's obviously going to be some inaccuracy down at that level due to length of meter leads etc, but the result is fairly clear.  You'll understand why I was checking the meter was working and I was reading it correctly though

       

       

      So from there onto the next test, lets try completely disconnecting RG1 and see if the Pi boots while using the LAN9512 1.8v 'output'.  Yes it does! 

       

      I think that's reasonably good indication that jamodio got it spot on, the lan9512 shouldn't be connected to the 1.8v plane and it's heat problems are going to be largely due to supplying current on it's 1.8v filter pin that it was never designed to do.

       

      So anyone willing to pull RG1 off a Pi and verify my results ?

        • 1. Re: RG1 1.8v regulator
          morgaine

          Wow.   That's worrying.

           

          PS. It would be nice if you could include the images here directly, thumbnails at least.  Picasa is somewhat annoying because of its multiple required Javascript sources, and Google is developing quite a habit of turning off free services anyway ... as well as becoming evil. :-P

          • 2. Re: RG1 1.8v regulator
            Nate1616

            Thanks for starting to test this theory out.  I would really like to see the results of removing the RG1 off the Pi.  To bad i dont have a Pi laying around to do this do.

            • 3. Re: RG1 1.8v regulator
              tmackay

              When my other Pis arrive I might be tempted to break out the soldering iron. In the mean time, I'm doing a bit of reading.

               

              Looking at figure 2.2 of the 9512 datasheet (http://www.smsc.com/media/Downloads_Public/Data_Sheets/9512.pdf) would it be possible to cut the 3.3V input to the internal core regulator and have the core logic powered by an external (more efficient) 1.8V source? I'm not sure if this chip will run that way or how oversimplified this diagram is but it might be easier and more power efficient than trying to cut the link to the external 1.8V plane.

               

              I'm guessing those VDD33IO pins do more than just feed into internal regulators though, or the chip would just run off 1.8V to start with.

              • 4. Re: RG1 1.8v regulator

                I think it may be time to contact SMSC, and find out whether it's OK

                to use the LAN9512 chip's 1.8V "output" pin to power other devices

                in parallel with another LDO regulator.

                 

                The datasheet, p. 41, at:

                   http://www.smsc.com/media/Downloads_Public/Data_Sheets/9512.pdf

                shows power dissipation of 763mW.  But that probably doesn't account

                for this scenario.  SMSC's tech support is available at:

                 

                https://www2.smsc.com/mkt/intforms.nsf/faemail

                • 5. Re: RG1 1.8v regulator

                  Wow.   That's worrying.

                  Well yeah.. but I think we've suspected what's going on since jamodio pointed out the error on the schematics.

                  PS. It would be nice if you could include the images here directly, thumbnails at least.  Picasa is somewhat annoying because of its multiple required Javascript sources, and Google is developing quite a habit of turning off free services anyway ... as well as becoming evil. :-P

                  My reason for using an external host for the pictures is fairly simple. Most forums I try to upload to seem to have ridiculous limits, like max size of 10k and a .JPG will upload but not a .jpg or .patch rendering the facility rather pointless. I also dislike the forums where you have to register and login to see the images, or where the column width is enforced and the image gets cropped. Finally I'm usually going to share these things with several different groups of people and a central point makes it easier.  I accept you may not agree with my reasons, but they are what they are.

                   

                  So, if you can suggest someplace that meets the following: 1. not javascript encrusted, 2. not part of the evil empire, 3. free, 4. reasonably permanent,  I'd be more than happy to use it instead.

                   

                  Just trying it here, not too bad with a 2MB size limit, but still scales down the image with the associated loss of detail.  So I'll at least try uploading stuff here too.

                  IMG_1909.JPG

                  • 6. Re: RG1 1.8v regulator

                    I'm guessing those VDD33IO pins do more than just feed into internal regulators though, or the chip would just run off 1.8V to start with.

                    Yeah, you'd have to assume they're used for 3.3v IO pins back towards the SoC at the very least. Not really clear if the internal regulator is from a single pin, or from many, or which one. So not clear if it's easier or not.

                    It's looking more like we need someone with a model A or who is prepared to pull the LAN9512 of the board to be able to measuer the RG1 current that way.  While I'm probably prepared to try that, I'm not there just yet

                    • 7. Re: RG1 1.8v regulator

                      I think it may be time to contact SMSC, and find out whether it's OK

                      to use the LAN9512 chip's 1.8V "output" pin to power other devices

                      in parallel with another LDO regulator.

                      If it was acceptable to use it as an output I'd expect to see something in the DC specs to tell you how much current it can supply.  I'd also suspect that running it in parallel with another regulator isn't going to be a good idea regardless.

                      • 8. Re: RG1 1.8v regulator

                        Just to expand on my original observations, the negative current I see on the output of RG1 seems to be due to it outputting 1.79v for a few seconds on initial powerup before stabilising at 1.804v. While the LAN9512 appears to power up at 1.805v and stay there.

                        • 9. Re: RG1 1.8v regulator
                          morgaine

                          selsinork wrote:

                           

                          So, if you can suggest someplace that meets the following: 1. not javascript encrusted, 2. not part of the evil empire, 3. free, 4. reasonably permanent,  I'd be more than happy to use it instead.

                           

                          Just trying it here, not too bad with a 2MB size limit, but still scales down the image with the associated loss of detail.

                           

                          Thanks.

                           

                          Aye, it's a problem indeed.  I think I'm going to use this "ARM revolution" to detach myself as much as possible from the various evil empires by hosting resources of various kinds myself on cheap and low-power ARMs, and removing them from the 3rd party sites.  It'll kill several birds with one stone.  It even makes sense in colos, because you can run a whole pile of ARMs within the typical least-cost rack power allocation.

                           

                          Back to running my own servers like in the early days before we succumbed to the dark side.

                           

                          Morgaine.

                          • 10. Re: RG1 1.8v regulator

                            Selsinork,

                             

                            >If it was acceptable to use it as an output I'd expect to see something in the DC specs to tell you how much current it can supply.  I'd also suspect that running it in parallel with another regulator isn't going to be a good idea regardless.

                             

                            right.  But I think in order to actually get this fixed it's going to take more than suspicions that there's a problem. If SMSC can be prompted to issue a clarification, then Element14 might take notice, and if they do, then maybe RPF might take notice.  Otherwise it looks like they will go on indefinitely saying the chip may be running a little warmer than expected, but it's not hurting anything.

                            • 11. Re: RG1 1.8v regulator

                              Well IMHO the simple fact that you can take RG1 off the board and have the Pi still work is good enough proof that there's a problem.

                               

                              I don't expect the RPF to listen, we've seen what happens to anyone suggesting there's a design flaw over on their forum. I think the best we can hope for is that Pete is still watching here and might take a look.

                               

                              Unless you have some decent technical contact within farnell/element14 who can objectively assess what we've found and then arrange an official approach to the RPF through avenues not available to us I don't see how to do much more.

                              Even with an official statement from SMSC you still need to get past the PR dept and get it into the hands of an engineer who's prepared to listen.

                              • 12. Re: RG1 1.8v regulator
                                John Beetem

                                People have reported very different IC3 (LAN9512) temperatures at the RasPi forum, which many ascribe to uncalibrated "digital" temperature sensors and I've suggested is due to how well IC3's ground pad is soldered.  I wonder if some of this variance is caused by different RG1 threshold voltages, where some RasPis generate 1.8V using RG1 and others using IC3, depending on who manufactured RG1?

                                 

                                Does anyone know if IC3's 1.8V is generated linearly or by a switching regulator?  If it's a switching regulator you should see ripple on a 'scope.

                                • 13. Re: RG1 1.8v regulator

                                  hard to be 100% sure, the datasheet isn't the best, and there's some stuff that coule be a switching regulator on the schematics..  but down at 20mV on the scope and I'm not seeing the sort of thing that's characteristic of a switching regulator, so I'd go with the core regulator being linear.

                                  • 14. Re: RG1 1.8v regulator
                                    tmackay

                                    I couldn't resist a little hardware hacking on a Saturday morning.

                                     

                                    My LAN9512 isn't running hot, only luke warm I would say, but I can guarantee a system hang by copying a file from an nfs mount to a usb flash drive in 10-20 seconds. USB keyboard is a little glitchy too. Tried 10W iPad charger and Dell monitor with integrated USB hub for power also without keyboard over ssh. That's motivation enough for me to tinker.

                                     

                                    Carefully, I cut the circuit traces from pins 15 and 38 on LAN9512 and the 1.8V side of C29 to the vias. I then very carefully soldered some wire between these three points. This more closely resembles how the circuit should be (minus the 100nF caps). (The 9512 reference design says 4u7 should be by pin 38 btw) See photo:

                                     

                                    IMG_0976.JPG

                                     

                                    Measurements taken before show 1804mV on both RG1 and C29. After modification I have 1797mV on RG1 and 1809mV on C29, so I am confident the regulators are now isolated. The effectiveness of my filter circuit is a little more dubious.

                                     

                                    Didn't fix the system hang copying over LAN to USB, but I can copy from LAN to the SD card (didn't think to test that previously). At least my Pi still works.

                                     

                                    Now that VDD18CORE is isolated from RG1 I can measure the current drain on RG1. More results to follow.

                                     

                                    [edit] After lifting RG1 and placing my exceedingly cheap multimeter in series with the output I measure about 20mA briefly, then 80mA briefly then 60-70mA for a while while booting then finally settling down to 50.5mA at the login prompt (presumably, no video attached, only power). Would have been nice to take a measurement before, I know, not very scientific of me.[/edit]

                                    • 15. Re: RG1 1.8v regulator

                                      John,

                                      > I wonder if some of this variance is caused by different RG1 threshold voltages...

                                       

                                      another possibility is some variation in the LAN chips, which have been

                                      seen to have different markings.  I can't decode them all, but possibly

                                      the last two characters, sg or tw, indicates Singapore vs. Taiwan factories.

                                       

                                      There is a list of boards and their variations here, but unfortunately there's

                                      no column for how hot the chips get.

                                       

                                      http://elinux.org/RaspberryPi_Boards

                                      • 16. Re: RG1 1.8v regulator

                                        Selsinork,

                                         

                                        >Unless you have some decent technical contact within farnell/element14 who can objectively assess what we've found and then arrange an official approach to the RPF through avenues not available to us I don't see how to do much more.

                                         

                                        Maybe Drew is following this thread and can get the right people involved.  I'm convinced that Pete isn't listening.  I think anyone who does pay attention will need to get clarification from SMSC, so might as well get the ball rolling on that.  Otherwise, I can imagine what a conversation with tech support might be like.

                                         

                                        tech support:  how can I help you?

                                        customer:  I removed RG1 and my board still works.  That seems to be proof that it's broken.

                                        tech support;  you say your board still works?

                                        customer:  yup.

                                        tech support: well, we're here to help customers whose board isn't working.

                                        customer: but I removed RG1.

                                        tech support: well, we're here to help customers who haven't removed components.

                                        customer: but the board runs hot

                                        tech support: we advise allowing plenty of ventilation.

                                        • 17. Re: RG1 1.8v regulator

                                          I'm convinced that Pete isn't listening.

                                          Yeah, I checked his profie on here yesterday. Doesn't look like he's posted anything for 3+ months.

                                           

                                          My only two thoughts were to either PM Pete directly on here, (but it seems that you need the recipient to approve you as a contact before you can do that), or to try a pm to Eben over on the other forums. The problem is going to be picking a subject line that doesn't get lost in the noise, and I'm an engineer so useless at that sort of thing

                                           

                                          You're right that the tech support route just isn't going  to work.

                                          • 18. Re: RG1 1.8v regulator

                                            I just posted a summary of the issue in the experts forum here:

                                             

                                            http://www.element14.com/community/thread/19261?tstart=0

                                            • 19. Re: RG1 1.8v regulator

                                              are you able to measure the temperature of the lan9512 with this mod in place?   I'm only getting arount 48C on any of thr Pi I have, which I don't consider too bad, certainly not the 'blisteringly hot' others have reported..  So either I have asbestos fingertips from too many years of burning them with soldering irons, or there's some other factor involved.

                                               

                                              Ideally we need to find one that runs hot, or how to duplicate that condition, and try this mod on it to see what difference it can make.

                                              • 20. Re: RG1 1.8v regulator

                                                another possibility is some variation in the LAN chips, which have been

                                                seen to have different markings.  I can't decode them all, but possibly

                                                the last two characters, sg or tw, indicates Singapore vs. Taiwan factories.

                                                My first board - one out of the first 2K built by the RPF - has this

                                                 

                                                LAN9512-JZX

                                                B1134-A1B17

                                                8R147769B

                                                STA-SG

                                                 

                                                runs at approx 48C give or take the variance of an MCP9803 i2c sensor stuck to the top

                                                 

                                                The newer ones are as follows (all from approx the same time)

                                                 

                                                B1217-A1B17

                                                8R150409A

                                                CTI-TW

                                                 

                                                B1218-A1B17

                                                8R150419A

                                                CTI-TW

                                                 

                                                B1218-A1B17

                                                8R150419A

                                                CTI-TW

                                                 

                                                B1217-A1B17

                                                8R150409A

                                                CTI-TW

                                                 

                                                B1218-A1B17

                                                8R150419A

                                                CTI-TW

                                                 

                                                B1217-A1B17

                                                8R150409A

                                                CTI-TW

                                                 

                                                untested for temperature so far..

                                                 

                                                 

                                                and the one I modified:

                                                 

                                                B1218-A1B17

                                                8R150303B

                                                CTI-TW

                                                 

                                                it appears that this one might be running slightly hotter, I've seen 50.5C on the sensor, but I can't be sure that's not down to how good the contact from sensor to chip is - I'm just taping the sensor down after all..

                                                • 21. Re: RG1 1.8v regulator
                                                  morgaine

                                                  Is the LAN9512 EOL'd?  I'm a bit surprised not to find it among Farnell's SMSC LAN9xxx products.

                                                  • 22. Re: RG1 1.8v regulator

                                                    It's available from digikey, mouser, RS etc.. also no obvious indication on the SMSC page that it's EOL, datasheets updated as recently as Feb this year, so I'd be surprised if it was. 

                                                    • 24. Re: RG1 1.8v regulator
                                                      tmackay

                                                      selsinork wrote:

                                                       

                                                      are you able to measure the temperature of the lan9512 with this mod in place?

                                                      I have an IR thermometer on its way from China which might take a few weeks. I might also be able to dig a thermocouple out of my junk box somewhere. The plan is to take temperature readings in various modes of operation when running the 1.8V plane off each regulator (RG1 and LAN9512) individually. Otherwise there is the finger test. Results to follow.

                                                       

                                                      Quick update before I go to work:

                                                      I found a thermistor from the Silicon Chip Multi-Purpose Fast Battery Charger kit from the Feb 1998 issue. Not sure what its specs are if anyone has this issue handy, otherwise I'll have to go digging for the plans or do a calibration. Here is a pic of the test setup:

                                                       

                                                      IMG_0999c.JPG

                                                       

                                                      The pinout for the 4-pin header is: GND, RG1OUT, Pi 1.8V plane, VDD18CORE

                                                      This will also allow for current measurements, particularly of interest is the direction of current from VDD18CORE to RG1OUT. Other current measurements in series with the regulator outputs may not be accurate when both regulators are connected due to additional resistance of the multimeter. This may tell us if the LAN9512 is sourcing or sinking current during normal operation. I suspect sourcing due to thermal images showing a cold RG1. The GND pin can be used to connect an external adjustable 1.8V source for further testing behaviour of LAN9512 in this unsupported mode of operation.

                                                       

                                                      Update:

                                                      Initial results were not definitive so I took a few more current measurements to maximize the drain on the 1.8V supply. I could get consistently 100-110mA with peaks of 130mA by playing back a 1080p video with omxplayer. I pushed some network traffic through for good measure which did have an observable effect on the equilibrium temperature.

                                                       

                                                      Thermistor resistance at room temperature (about 20 degrees C) was approx 110KOhm, so using a temperature chart for a 100K thermistor we have (roughly, at equilibrium):

                                                      Running 1.8V plane from RG1 57.5KOhm (approx 37 degrees C)

                                                      Running 1.8V plane from LAN9512 53.7KOhm (approx 39 degrees C)

                                                      Holding thermocouple in hands 63.5KOhm (approx 35 degrees C)

                                                       

                                                      These temperatures are fairly rough of course, but give a relative indication of temperature. Not the dramatic effect I was expecting, but it does run hotter as expected with that extra drain through the internal regulator, not blisteringly hot though.

                                                       

                                                      Perhaps in the worst case if VDD18CORE is slightly higher than that of the output of RG1 then not only does it power the 1.8V plane, but leaks back through RG1 to ground. In which case you may be better off removing RG1 so at least the drain on the LAN chip is capped at around 100mA.

                                                      • 25. Re: RG1 1.8v regulator

                                                        Just adding it here for those not following all the different threads..

                                                         

                                                        I asked SMSC tech support:

                                                         

                                                        "I'm evaluating a design using your LAN9512 device. Can you tell me if it's

                                                        acceptable to use VDD18CORE to supply 1.8v to external devices and if so what

                                                        current can be supplied ?

                                                        The datasheet only describes it as "Digital Core +1.8V Power Supply Output" but

                                                        offers no details on if it's useable to power external devices or what current

                                                        it can supply."

                                                         

                                                        Their reply:

                                                        We have received your request for Technical Support.  The following reviews.

                                                        SMSC Technical Support Request # 534992-DD1256

                                                        31/07/2012 10:06 ISaturle: 

                                                        Hi Iain,

                                                         

                                                        VDD18 is not intended to power external nets.  Equally, it's not intended to ever be driven by external sources. 

                                                        • 26. Re: RG1 1.8v regulator
                                                          tmackay

                                                          My second order of Raspberry Pis arrived earlier in the week. A quick check shows one of them is running slightly warmer than the rest, not too much, I can still hold my finger on the LAN chip. I measure 1837mV at RG1 compared to 1793mV on one of the cooler ones (at idle, unmodified boards). Perhaps the LAN9512 core is running over voltage due to the external source and hence a bit hotter in this case. There may be multiple scenarios depending on components.

                                                          I don't expect it will reduce the life of the chip unless it gets really hot, so I'll leave the rest alone unless LAN chips start dying all over the place.

                                                          • 27. Re: RG1 1.8v regulator
                                                            John Beetem

                                                            Troy Mackay wrote:

                                                             

                                                            My second order of Raspberry Pis arrived earlier in the week. A quick check shows one of them is running slightly warmer than the rest, not too much, I can still hold my finger on the LAN chip. I measure 1837mV at RG1 compared to 1793mV on one of the cooler ones (at idle, unmodified boards). Perhaps the LAN9512 core is running over voltage due to the external source and hence a bit hotter in this case. There may be multiple scenarios depending on components.

                                                            I don't expect it will reduce the life of the chip unless it gets really hot, so I'll leave the rest alone unless LAN chips start dying all over the place.

                                                            That's consistent with my limited knowledge of voltage regulators.  My understanding is that if two positive linear regulator outputs are connected to the same node, whichever has the higher voltage reference will supply all the current.  The one with the lower reference will shut off, satisfied that it doesn't need to do any work.  RG1 probably has more precise regulation than IC3 (LAN), so it's more likely that +1V8 voltage above 1.800V is sourced by IC3 due to manufacturing variance.  Feel free to correct my understanding if I've got it worng.

                                                            • 28. Re: RG1 1.8v regulator

                                                              My understanding is that if two positive linear regulator outputs are connected to the same node, whichever has the higher voltage reference will supply all the current.  The one with the lower reference will shut off, satisfied that it doesn't need to do any work. 

                                                              I'm not convinced that one will shut off. When you look at the equivalent circuit for these lm1117 style regulators in the datasheets there's nothing particularly clever looking in the design.

                                                              Simple ohms law on the other hand gives a good idea that when two are connected in parallel the one with the lowest resistance path will probably end up supplying the most current - at least until a higher voltage offsets the resistance difference.

                                                              When we're talking about something that has a large power/ground plane under it then it's likely going to be a toss-up on manufacturing tolerances - which regulator is a couple of mV higher or lower.. Unlikely anything will ever practically manage to keep at exactly 1.8000000000v across temperature and load variations, so things may even swap over as the board warms up, or when you stress the GPU playing some video etc.  Every board will be different and everyone will have different ambient temperature, peripherals, cpu usage, whatever..

                                                              • 29. Re: RG1 1.8v regulator
                                                                tmackay

                                                                John Beetem wrote:

                                                                 

                                                                RG1 probably has more precise regulation than IC3 (LAN), so it's more likely that +1V8 voltage above 1.800V is sourced by IC3 due to manufacturing variance.

                                                                Just confirming that does indeed appear to be the case. I popped RG1 off and still measure 1837mV. IC3 still feels about the same temperature wise.

                                                                edit: Scratch that last statement. Playing back video over network, IC3 is running considerably hotter, at the limit of my pain threshold, my finger is still sore. Guess RG1 was still providing some relief. Replaced RG1 and it's still a bit warmer than before, might need a touch more solder.

                                                                • 30. Re: RG1 1.8v regulator
                                                                  PeteL

                                                                  Hi Troy & all

                                                                   

                                                                  Since this thread and Coder27's thread are actually all about the same issue, can we recombine or something.  Alternatively I'll limit my replies to the one or other so at least we can keep the flow going.

                                                                   

                                                                  People coming to the forum will recognise a 'hot' SMSC if they have one, so that might be the best place?

                                                                   

                                                                  Comments / Ideas?

                                                                   

                                                                  Playing back video ramps the current requirement of the BCM considerably, again with RG1 o/c can you measure the surface temp of the SMSC?

                                                                   

                                                                   

                                                                  Cheers

                                                                   

                                                                  Pete

                                                                  • 31. Re: RG1 1.8v regulator
                                                                    morgaine

                                                                    Nice to see you here again, Pete.

                                                                     

                                                                    My finger is quite toasty now from all the finger tests on my very hot LAN9512.  Looking forward to your input on this!

                                                                     

                                                                    Morgaine.

                                                                    • 32. Re: RG1 1.8v regulator

                                                                      I came across a document "Standards for School Premises" at

                                                                        http://www.plymouth.gov.uk/standards_for_school_premises_dfes-3.pdf

                                                                      that says:

                                                                       

                                                                         Hot Surfaces   

                                                                         83. Some pupils are more at risk than others from hot surfaces. In special

                                                                          schools, nursery schools and in teaching accommodation used by nursery

                                                                          classes, the surfaces of radiators and exposed pipes located where they

                                                                          might be touched by a pupil must not become hotter than 43 degrees C.

                                                                       

                                                                      This probably isn't directly relevant to electronic devices, but it might suggest

                                                                      that uncovered electronics with blisteringly hot chips may be considered a

                                                                      safety hazard in schools.

                                                                       

                                                                      In California, hot surfaces of 140 degrees F (60 degrees C) are considered

                                                                      a safety hazard in the workplace.

                                                                      http://www.dir.ca.gov/oshsb/hot_surfaces_isor.pdf

                                                                      • 33. Re: RG1 1.8v regulator
                                                                        morgaine

                                                                        If you recall our "Finger Contact Survival Time" (:-) testing over in this thread , although initial contact temperature on my Pi was such that pure instinctive body reaction tore the finger away in a fraction of a second to avoid harm, subsequent fingers survived contact for progressively longer periods, indicating that the LAN9512 has low heat capacity and/or high thermal resistivity in its surface material.

                                                                         

                                                                        Those tests tell me that it's not really a danger in the safety sense.  The temperature is below ignition point for all common materials, and there's not enough of a heat reservoir there to maintain its temperature if coupled to anything that is thermally conducting.  The main danger to humans is probably from the instinctive reaction:  a schoolkid's sudden violent withdrawal of their hand could knock out another kid's eye or break something.

                                                                         

                                                                        The other thing that those tests tell me is that the main problem doesn't seem to be too much heat being generated but not enough heat being conducted away through the solder connections, because the surface of the device isn't able to conduct nor radiate much heat away at all.

                                                                         

                                                                        For reference, link to post with thermal image showing the 65.1C peak temperature on LAN9512 .

                                                                         

                                                                        PS. Because of the low heat capacity and/or high thermal resistivity of the surface material, a thermocouple attached to the surface is likely to indicate a lower temperature than a thermistor.  The thermocouple is entirely metallic and hence very likely to be a good conductor of heat away from the device.  A non-contact measurement like Remy's is best here.

                                                                         

                                                                        Morgaine.

                                                                        • 34. Re: RG1 1.8v regulator

                                                                          Yes, I recall the "Finger Contact Survival Time" discussion,

                                                                          but I'm not sure how relevant it is. As you say, if you pull away

                                                                          the first finger in a fraction of a second, you can use subsequent

                                                                          fingers for longer.  But the safety concern is whether the first

                                                                          finger will get burned if not pulled away in a fraction of a second,

                                                                          because younger children, older adults, and the disabled are

                                                                          assumed to have slower reflexes.

                                                                          • 35. Re: RG1 1.8v regulator

                                                                            Pete,

                                                                             

                                                                            Here's some additional data.

                                                                             

                                                                            To hopefully make these reasonably repeatable, here's some detail of the setup I've been using

                                                                             

                                                                            2012-07-15-wheezy-raspbian.img no firmware/kernel upgrades done.

                                                                            overscan disabled

                                                                            1600x1200 Dell 2007FP monitor

                                                                            all 'idle' readings taken while at a text based login prompt, X has not been started

                                                                            'playing video' readings taken after running startx and then omxplayer from a terminal to play a 720p h264 mkv file

                                                                            temperature readings taken with a MCP9803 i2c temperature sensor on top of the lan9512

                                                                            5v applied via the GPIO header with 16/0.2 cable and I'm arranging that TP1-TP2 reads 5.00v

                                                                             

                                                                            Ambient, today:

                                                                            outside 20C

                                                                            inside 26C

                                                                            50.3% RH

                                                                            1005 hPa

                                                                             

                                                                            at each step I'm giving the board 15mins to reach equlibrium

                                                                            The blue column at the end is the unloaded voltage reading from RG1 while it's off the board.

                                                                             


                                                                            RG1 on boardRG1 Removed
                                                                            SerialIC3 idleIC3 playing videoIC3 1.8vIC3 idleIC3 temp playing videoRG1 Voltage
                                                                            FN12071161850C / 1807mV54C / 1805mV1807mV50C / 1806mV54C / 1804mV1806mV
                                                                            FN12072066451C / 1822mV53.5C / 1819mV1822mV50C / 1822mV53.5C / 1819mV1803mV
                                                                            FN12072617851C / 1831mV53.5C / 1828mV1831mV50C / 1832mV53.5C / 1828mV1795mV
                                                                            SC888 20120317135450C / 1807mV52C / 1806



                                                                             

                                                                            Sorry, but I won't be pulling RG1 off that last board, hope you understand why

                                                                             

                                                                            I have a couple of boards from FN120720xxx FN120722xxx, but as my results are mostly similar I've just picked either end of the range I have along with a couple in the middle.

                                                                            • 36. Re: RG1 1.8v regulator
                                                                              PeteL

                                                                              Selsinork

                                                                               

                                                                              Thank you so much for this great piece of work, really helpful.  Cannot wait to try some FN1204xxxx,FN1205xxxxx boards with the same configuration.

                                                                               

                                                                              I'll let you know how I get on.

                                                                               

                                                                              (I wonder if this post will dissolve into the Ether as soon as I post? )

                                                                               

                                                                              Cheers

                                                                               

                                                                              Pete

                                                                              • 37. Re: RG1 1.8v regulator
                                                                                morgaine

                                                                                PeteL wrote:

                                                                                 

                                                                                (I wonder if this post will dissolve into the Ether as soon as I post? )

                                                                                 

                                                                                You're in luck Pete!  The SHA-512 of the characters in the subject line multiplied by the current distance to Jupiter in furlongs added to the day of the week is not prime!

                                                                                 

                                                                                Or maybe Loki was so stunned at selsinork's awesome chart that he forgot his usual duties.

                                                                                 

                                                                                Morgaine.

                                                                                • 38. Re: RG1 1.8v regulator
                                                                                  morgaine

                                                                                  Pete, if your examination of Pi design around the LAN9512 leads to board changes in that area, you might wish to consider the problem of self-powered USB hubs attempting to power the Pi upstream through their A-B lead, which typically fails and sends the Pi into a rapid continuous reboot cycle and a consequent rapid power cycling of attached HDMI equipment.

                                                                                   

                                                                                  I reported it in a thread here -- http://www.element14.com/community/thread/19316?tstart=0

                                                                                   

                                                                                  Unfortunately this affects an official Farnell "Pi Accessory" hub, and I'm sure it's not the only one.

                                                                                   

                                                                                  Morgaine.

                                                                                  • 39. Re: RG1 1.8v regulator
                                                                                    jamodio

                                                                                    Catching up after some vacations.

                                                                                     

                                                                                    NO IT IS NOT OK to use the VDD18CORE pins as an output supply, they pins are there only to hookup the

                                                                                    decoupling caps for the internal regulator.

                                                                                     

                                                                                    Glad you guys had a chance to test the theory, if the Gerbers match the schematics, and the actual PCB match the Gerbers, that's a hardware error on the Rpi, I don't think that there is much more to say.

                                                                                     

                                                                                    -J

                                                                                    • 40. Re: RG1 1.8v regulator
                                                                                      Tooms

                                                                                      Hi all and hallo to the forum from Copenhagen Denmark

                                                                                       

                                                                                       

                                                                                      I have done some testing to try out what your guys saying.

                                                                                       

                                                                                      1. using switchmode power
                                                                                      2. the LAN9512 is having an buildin LDO there is haveing higher volt level then the LDO RG1 has and because of this then the LAN9512 LDO is powering the other items there is using the 1V8 and the LDO RG1 is not doing any work.

                                                                                       

                                                                                      So i was thinking why not just try add some ebay LM2596 switchmode boards in paralle with the two LDO RG2 3V3 and RG1 1V8 to see if i can get it to use less power and get the LAN9512 to run cooler, so i just add some wires to the RG1 and RG2 and then add the LM2596 with the volt level just an small bit higher then the RG1/LAN9512 and RG2 was showing and by this let the LM2596 do the work..

                                                                                       

                                                                                      To the raspberry i connected the buildin network card to the switch and then another usb wireless netcard connected to my wireless network with WPA2 encryption and then an usb webcam to have some things to use power via the network and usb ports.

                                                                                      I then ask the raspberry to take 10000 single images from the webcam with ffmpeg and at the same time i copy some files over the wireless network, this process was running for about 30-45 minutes each time to get the temperature to get stabile

                                                                                       

                                                                                      Background rum temperature is 25.5C (measured with Fluke 54II)

                                                                                       

                                                                                      The Volt level is measured with an Fluke 8846A

                                                                                       

                                                                                      The Amp reading is the reading from the powersuppy (HP 6632B)


                                                                                      This is photo of the setup (and alot other things sorry for the mess)

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                      Here is test 1

                                                                                      Work: Idle mode
                                                                                      Power: Power from buildin RG1 and RG2 LDO
                                                                                      Amp reading = 541.10 mA
                                                                                      RG2 5V0 pin = 4.96150v
                                                                                      RG1 3V3 pin = 3.32753v
                                                                                      RG1 1V8 pin = 1.81029v
                                                                                      Raspi watt =  (4.96150v * 0.54110A) = 2.68466W
                                                                                      temperature - sorry have not taking any images of this

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                      Here is test 2

                                                                                      Work: Idle mode
                                                                                      Power: Power from the onboard LDO and two paralle switchmode LM2596 there is set to 1V8 and 3V3
                                                                                      Amp reading = 443.20 mA
                                                                                      RG2 5V0 pin = 4.98338v
                                                                                      RG1 3V3 pin = 3.35214v
                                                                                      RG1 1V8 pin = 1.84575v
                                                                                      Raspi watt =  (4.98338v * 0.44320) = 2.20863W

                                                                                      Here is an IR images of the PI at this test and the temperature is 49.5C on the LAN9512

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                      Here is test 3

                                                                                      Work: capturing images from webcam and copy data via the wireless network
                                                                                      Power: Power from buildin RG1 and RG2 LDO
                                                                                      Amp reading = 671.51 mA
                                                                                      RG2 5V0 pin = 4.93466v
                                                                                      RG1 3V3 pin = 3.32762v
                                                                                      RG1 1V8 pin = 1.81068v
                                                                                      Raspi watt = (4.93466V * 0.67151A) =  3.31367W

                                                                                      Here is an IR images of the PI at this test and the temperature is 59.2C on the LAN9512

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                      Here is test 4

                                                                                      Work: capturing images from webcam and copy data via the wireless network
                                                                                      Power: Power from the onboard LDO and two paralle switchmode LM2596 there is set to 1V8 and 3V3
                                                                                      Amp reading = 553.19 mA
                                                                                      RG2 5V0 pin = 4.96022v
                                                                                      RG1 3V3 pin = 3.34853v
                                                                                      RG1 1V8 pin = 1.84341v
                                                                                      Raspi watt = (4.96022v * 0.55319A) =  2.74394W

                                                                                      Here is an IR images of the PI at this test and the temperature is 51.3C on the LAN9512

                                                                                       

                                                                                       

                                                                                       

                                                                                       

                                                                                      So it seems by add two switchmode power suppy modules for the 3.3V and 1.8V instedt of the LDO then it is using 0.5 watt less power and is running around 8C cooler on the LAN9512.

                                                                                      I guess it will be even better if removing the LDO's from the board and only use the switchmode modules like the ebay LM2596 modules i got from china.

                                                                                       

                                                                                       

                                                                                      as a side note, i have also bypassed the USB fuses with direct 5v at the fuse on the usb side and i need this to be powering the usb netcard and webcam.

                                                                                       

                                                                                       

                                                                                       

                                                                                      Tooms

                                                                                      • 41. Re: RG1 1.8v regulator
                                                                                        electron2

                                                                                        As shown in Troy Mackay's post on Jul 28 it seems to me that we could mod our PI's to work more as the chips were designed.

                                                                                         

                                                                                        I think that this could make the PI more stable, from the looks of it.

                                                                                         

                                                                                        I am not a designer Just an old tech, but I think we need to find a way to FIX what we now know is an error in the board.

                                                                                         

                                                                                        So could someone do some practical testing to see if there is something that can be done to easly fix the current board, rather than wait for RPI foundation to fix it by waiting for a board redesign?

                                                                                        • 42. Re: RG1 1.8v regulator
                                                                                          Tooms

                                                                                          i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

                                                                                           

                                                                                          so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

                                                                                           

                                                                                           

                                                                                          Tooms

                                                                                          • 43. Re: RG1 1.8v regulator

                                                                                            So could someone do some practical testing to see if there is something that can be done to easly fix the current board, rather than wait for RPI foundation to fix it by waiting for a board redesign?

                                                                                            I think we'd all like an easy fix, but with the information we have available today what Troy did is likely the best we can do. Cutting three tracks and some fiddly at best soldering on of some wire links isn't for everyone though.

                                                                                             

                                                                                            Beyond that we need to wait to see what Pete comes up with.  If the full gerbers were available someone would have a look and see if there was an easier way to seperate the lan9512's 1.8v from the rest of the board, but even then from what the schematics suggest there's probably a 1.8v plane on layer 5 which could make it essentially impossible...  If we're very lucky there might be a single via in a favourable place that could be carefully drilled out, but that's just about as bad as Troys wire links.

                                                                                             

                                                                                            Tooms idea of a marginally higher 1.8v feed from an external switching regulator may be the simplest after-market mod to accomplish even if it's not ideal. There seems to be a fair bit of interest all round in replacing the linear regulators, several designs have surfaced already.

                                                                                            • 44. Re: RG1 1.8v regulator
                                                                                              jamodio

                                                                                              It would help to have a nice set of Gerber files with the current pcb layout to take a look a the traces and vias to chose what is the best course of action

                                                                                              before cutting stuff.

                                                                                               

                                                                                              One option could be to just lift the two VDD18CORE pins, put togeher a small board that can be placed on top where the logo is with the 3.3 and 1.8

                                                                                              swtiched regulators, there are some very efficient and small ones like the LMZ10501 that can handle up to 1A and includes the FET and inductor

                                                                                              on the chip, add the decoupling caps for VDD18CORE on this board and run a wire to those pins. With some work you could manage to have

                                                                                              through hole pads to match the pads for the existing regulators.

                                                                                               

                                                                                              I think there are two or three tiny ceramic caps that will get hidden under the add-on board. It may work ...

                                                                                               

                                                                                              My .02

                                                                                              -J

                                                                                              • 45. Re: RG1 1.8v regulator
                                                                                                tmackay

                                                                                                I'm certainly no engineer, so take what I have to say next with a grain of salt. It might be that you could get away with just cutting the 3 traces. The VDD18CORE pins of IC3 are linked internally and I have gotten away with running regulators without the decoupling/filter capacitors in the past. This would certainly be running out of spec, whether or not it is worse than forcing in current from an external higher potential source I don't know. I'll do some more testing when my IR Thermometer arrives.

                                                                                                • 46. Re: RG1 1.8v regulator
                                                                                                  jamodio

                                                                                                  Even if you are able to place the decoupling caps not close as recommended to the pins, something is better than nothing.

                                                                                                   

                                                                                                  The internal regulator has no internal capacitance at all, running LDOs without or with the wrong caps may produce oscillation and not a reliable

                                                                                                  power source for the rest of the device.

                                                                                                   

                                                                                                  Here is an article that talks a little bit about the subject.

                                                                                                   

                                                                                                  PS. While datasheets are not always 100% accurate, complete or comprehensive, if a part says it needs a capacitor you should put the capacitor.

                                                                                                   

                                                                                                  -J

                                                                                                  • 47. Re: RG1 1.8v regulator

                                                                                                    maybe you could replace RG1 with a red LED.    A 1.4v

                                                                                                    forward voltage drop, leaving 1.9v, might be perfect to

                                                                                                    overpower the LAN chip, but still within 10% tolerance

                                                                                                    of 1.8v.

                                                                                                     

                                                                                                    Or maybe element14 will accept a RMA for a hot LAN chip

                                                                                                    and replace it with a board that runs cooler.

                                                                                                     

                                                                                                    p.s.

                                                                                                      I see this issue has made it to the other forum.

                                                                                                     

                                                                                                    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=12387&start=23

                                                                                                     

                                                                                                    edited to add:

                                                                                                     

                                                                                                    jamodio, I see your 25 July 2012 post in the other forum in this thread:

                                                                                                    http://www.raspberrypi.org/phpBB3/viewtopic.php?t=6050&p=144439

                                                                                                    • 48. Re: RG1 1.8v regulator
                                                                                                      jamodio

                                                                                                      I reported the problem while ago on the "other forum" but since I'm a concern troll probably didn't count ....

                                                                                                       

                                                                                                      -J

                                                                                                      • 49. Re: RG1 1.8v regulator
                                                                                                        tmackay

                                                                                                        My IR thermometer arrived yesterday and I was able to take some more measurments. The laser sight is mounted off to the side, so it is necessary to scan around to find the hot spot. Measurements taken after 20min of video playback over network.

                                                                                                         

                                                                                                        FN120508290 The first board the mod was applied to, still in a configuration where I can switch between the 1.8V power sources with a jumper.

                                                                                                          Powered from RG1 exclusively

                                                                                                            RG1 ____mV/IC3 ____mV idle (I forgot to measure this, will edit later as it might give an indication of each regulators ouput as a function of load)

                                                                                                            RG1 ____mV/IC3 ____mV playback

                                                                                                            45.7C

                                                                                                         

                                                                                                          Powered from IC3 exclusively

                                                                                                            RG1 ____mV/IC3 ____mV idle

                                                                                                            RG1 ____mV/IC3 ____mV playback

                                                                                                            49.1C - hot spot seems to be larger

                                                                                                         

                                                                                                        FN120744907 The second board which seemed to be running a bit warmer from the beginning

                                                                                                          Unmodified (RG1 removed and replaced in previous test. Heat stress may have influenced result)

                                                                                                            1837mV idle

                                                                                                            49.9C playback

                                                                                                         

                                                                                                          RG1 removed

                                                                                                            1837mV idle

                                                                                                            50.7C playback

                                                                                                         

                                                                                                          Mod applied

                                                                                                            RG1 1795mV/IC3 1845mV idle

                                                                                                            RG1 ____mV/IC3 ____mV playback

                                                                                                            46.0C - 49.5C (initially 46.0C after 20mins video playback, but it continued to rise for another 5 minutes or so)

                                                                                                         

                                                                                                        I thought I was getting consistent results until that last measurement. Not sure what happenned, maybe it needs more time to equilibriate or there was an action scene. I measured again after leaving it overnight and still read 47.2C and climbing after at least 20 mins _at idle_ (lan plugged in, but no traffic, no video playback), then after another 10 minutes back down to 46.0C. Maybe this is normal, at least we seem to have elliminated the dependance on video playback.

                                                                                                         

                                                                                                        The results seem to suggest that powering the 1.8V rail from IC3 might account for up to 4 degrees higher temperature on IC3. Looks like there might be quite a bit of variation in the LAN9512 chips based on the observed variation of VDD18CORE voltage so some may be affected more so than others.

                                                                                                         

                                                                                                        This doesn't really confirm if this bug is the source of the _really_ hot LAN chips, but my chips don't seem to be in that category anyway (50C seems to be the norm from what I see). Perhaps some chips handle this extra current drain more gracefully than others though.

                                                                                                         

                                                                                                        Here is the second attempt at the mod

                                                                                                        IMG_1026.JPG

                                                                                                        • 50. Re: RG1 1.8v regulator
                                                                                                          tmackay

                                                                                                          Tooms wrote:

                                                                                                           

                                                                                                          i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

                                                                                                           

                                                                                                          so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

                                                                                                           

                                                                                                           

                                                                                                          Tooms

                                                                                                          The microsope is really handy (and didn't cost me a cent), you'd be surprised what you can do when you can see what it is you are doing. I haven't even done a lot of SMD work. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

                                                                                                          • 51. Re: RG1 1.8v regulator
                                                                                                            jamodio

                                                                                                            I really don't know how much effort to put on modifying the existing boards, what should happen is the RPF people acknowledge the problem, come up with a workaround, fix it for future boards and analyze the long term effects of THEIR ERROR.

                                                                                                             

                                                                                                            Don't think anybody will be open to a massive recall, but the right thing to do is TO FIX THE ERROR.

                                                                                                             

                                                                                                            My .02

                                                                                                            -J

                                                                                                            • 52. Re: RG1 1.8v regulator
                                                                                                              tmackay

                                                                                                              For $38 I don't expect a great deal of support, but I do expect that for a first revision board shipped naked without accessories or a case in limited numbers that it was never intended for the classroom in this form. More likely their target was developers and hackers to help mature the product, find bugs and develop software. I would hope that there will be future revisions, debugged, upgraded, shipped with a case and basic accessories, but I'm happy to tinker about with what I have; that is, after all, what I bought it for.

                                                                                                              • 53. Re: RG1 1.8v regulator
                                                                                                                jamodio

                                                                                                                Well they missed the target for about couple of million miles. At the development phase price is irrelevant, and on the production phase what matters is cost, and not just components and assembly, you have to factor in that you will also need people and systems if you pretend to do a professional and serious job.

                                                                                                                 

                                                                                                                Being a charity or non-profit doesn't mean you have to cry all the time about it, I'm associated with non-profits that deal with huge piles of money and have a full time staff to do the organization's job to deliver on their mission and goals.

                                                                                                                 

                                                                                                                I think the argument "you get what you paid for" is very lame, I really don't care much about how much I paid for it or even if I had to pay much more to be part of what was promised to be an initiative to improve education on computer science.

                                                                                                                 

                                                                                                                There are no clear indications that there will be future versions or revisions and trying to obtain any information on that front is almost impossible. The only thing they keep talking about is the model "A" which is the same thing less few components and the camera module.

                                                                                                                 

                                                                                                                Still is a nice gadget to play with eLinux.

                                                                                                                 

                                                                                                                -J

                                                                                                                • 54. Re: RG1 1.8v regulator
                                                                                                                  morgaine

                                                                                                                  jamodio wrote:

                                                                                                                   

                                                                                                                  the right thing to do is TO FIX THE ERROR.

                                                                                                                   

                                                                                                                  My guess is that fixing the error(s) is ongoing right now, and that this is why Pete has returned to the job.

                                                                                                                   

                                                                                                                  There's total silence from RPF about it only because they can't yet figure out how to spin this into "Our perfect and faultless design is now even more perfect and faultless!".  But I'm sure that Liz will find a way.

                                                                                                                  • 55. Re: RG1 1.8v regulator
                                                                                                                    John Beetem

                                                                                                                    jamodio wrote:

                                                                                                                     

                                                                                                                    There are no clear indications that there will be future versions or revisions and trying to obtain any information on that front is almost impossible. The only thing they keep talking about is the model "A" which is the same thing less few components and the camera module.

                                                                                                                    Ironically, the Model A fixes the 1.8V regulator problem by not populating the LAN9512 , which also allows RasPi to run in a closed plastic case w/o heat problems.  Moderators at the RasPi Forum like to point out that the BCM2835 is used in cell phones without heat problems.  I don't recommend asking them how many cell phones have LAN9512 chips.

                                                                                                                    • 56. Re: RG1 1.8v regulator
                                                                                                                      jamodio

                                                                                                                      It was a good sign that Pete briefly showed up around here and somehow noticed and acknowledged that there are problems, but I'm not quite sure how much leverage he has.

                                                                                                                       

                                                                                                                      On the thread he showed up and mentioned "the list," I asked about "what else is on the list?" and the only thing I got so far is white noise.

                                                                                                                       

                                                                                                                      I already gave up trying to understand or figure what is going on with RPF, got tired of the default reaction and answer that "if there is something wrong with the Rpi the problem is YOU".

                                                                                                                       

                                                                                                                      -J

                                                                                                                      • 57. Re: RG1 1.8v regulator
                                                                                                                        morgaine

                                                                                                                        John Beetem wrote:

                                                                                                                         

                                                                                                                        Moderators at the RasPi Forum like to point out that the BCM2835 is used in cell phones without heat problems.

                                                                                                                         

                                                                                                                        The moderators live in a fanboi partition of reality where facts are an inconvenient irrelevance.  The BCM2835 is not known to have been used in anything other than Roku 2 until the Pi, and no BCM28xx series VideoCore has ever been used in a cellphone.

                                                                                                                         

                                                                                                                        It's the same odd partition of reality in which the Pi is called a "low power consumption" computer, the same "low power" that caused plastic components in that balloon payload to melt, and the same "low power" that doesn't allow me to keep my finger on the LAN9512 for longer than reflex time.

                                                                                                                         

                                                                                                                        Pity that XKCD isn't too interested in us.  There's enough material here for volumes.

                                                                                                                         

                                                                                                                        Morgaine.

                                                                                                                        • 58. Re: RG1 1.8v regulator

                                                                                                                          Troy,

                                                                                                                          You wrote:

                                                                                                                          "More likely their target was developers and hackers to help mature the product, find bugs and develop software."

                                                                                                                           

                                                                                                                          I think that is a widely held misconception.  Liz has explicitly said the

                                                                                                                          product is not in beta test.  Eben has explicitly said it is for sale to

                                                                                                                          anyone, not just developers and hackers.  If they were wanting to

                                                                                                                          find bugs and mature the product, they would have a highly visible

                                                                                                                          bug tracking system, and they would be eager to hear complaints. 

                                                                                                                          Instead they ban people who complain, labelling them "concern trolls". 

                                                                                                                          Jamodio ought to be a hero on the RPi forum for finding what is probably

                                                                                                                          the most serious design error.  Instead, he is banned as a concern troll.

                                                                                                                           

                                                                                                                          JamesH has made clear that they have no intention of disclosing

                                                                                                                          defects to potential buyers, and Abishur banned the guy yesterday

                                                                                                                          who advocated disclosing the known USB problems, and who said

                                                                                                                          he wouldn't have bought his RPi had he known.  Certainly they don't

                                                                                                                          show even the slightest bit of sympathy for those who end up

                                                                                                                          feeling duped.

                                                                                                                           

                                                                                                                          So my impression is that their target market is the unsuspecting

                                                                                                                          buyer who is blinded by the low price.  I think they are afraid that

                                                                                                                          their sales would dry up if they disclosed that the product isn't finished,

                                                                                                                          and they seem to think that they can't afford to lose the sales to those

                                                                                                                          who end up feeling duped.

                                                                                                                          • 59. Re: RG1 1.8v regulator

                                                                                                                            My IR thermometer arrived yesterday

                                                                                                                            I was looking at picking one up, but noticed that even rather expensive ones seem to have a minimum measurement 'spot' of something around 20mm which is rather larger than the lan9512. I was wondering just how that affects the readings..  Presumably they average the total emissions over whatever is in the sensors view somehow.

                                                                                                                             

                                                                                                                            Like you I don't have a Pi that runs as hot as some reports, and without one it's difficult to form a theory on what the cause is.

                                                                                                                            • 60. Re: RG1 1.8v regulator

                                                                                                                              . I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

                                                                                                                              Definately... I even went and looked at prices for a new one

                                                                                                                              • 61. Re: RG1 1.8v regulator

                                                                                                                                I think the argument "you get what you paid for" is very lame,

                                                                                                                                Possibly true.  My take on it is that something that's agressively designed down to a very low cost inevitably leads to compromises, doesn't matter if it's the RPF or IBM.  You have to account for that somehow and expecting the same results as something designed to a 10x greater cost with a huge R&D budget behind it just isn't realistic.

                                                                                                                                 

                                                                                                                                We may not like all the compromises, but it's done now. Hopefully a potential version 2 can improve things.

                                                                                                                                • 62. Re: RG1 1.8v regulator

                                                                                                                                  "Our perfect and faultless design is now even more perfect and faultless!".

                                                                                                                                  That particular aspect of the mantra is one that really annoys me. Especially when Pete comes here with the 'flaws and fixups' thread and seems quite open that there are issues he's looking at.

                                                                                                                                  • 63. Re: RG1 1.8v regulator

                                                                                                                                    If they were wanting to

                                                                                                                                    find bugs and mature the product, they would have a highly visible

                                                                                                                                    bug tracking system,

                                                                                                                                    Yeah, it's long past the point where the blog and forum format outlived it's usefulness - I'd argue mid April when the first boards were delivered was when it should have changed. The Raspbian site makes them look so much better and they probably have less people and resources, so it's not hard.

                                                                                                                                     

                                                                                                                                    Jamodio ought to be a hero on the RPi forum for finding what is probably

                                                                                                                                    the most serious design error. 

                                                                                                                                    Agreed. I haven't looked recently, but I noticed that they basically just blanked him when he posted it which, to me, says a lot.

                                                                                                                                    • 64. Re: RG1 1.8v regulator
                                                                                                                                      Tooms

                                                                                                                                      Troy Mackay wrote:

                                                                                                                                       

                                                                                                                                      Tooms wrote:

                                                                                                                                       

                                                                                                                                      i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

                                                                                                                                       

                                                                                                                                      so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

                                                                                                                                       

                                                                                                                                       

                                                                                                                                      Tooms

                                                                                                                                      The microsope is really handy (and didn't cost me a cent), you'd be surprised what you can do when you can see what it is you are doing. I haven't even done a lot of SMD work. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

                                                                                                                                       

                                                                                                                                      Hi

                                                                                                                                       

                                                                                                                                      yes i am only having an magnifying lamp the glass ones with 40 leds and it is not very good so i have been missing this for an long time..

                                                                                                                                       

                                                                                                                                      I ask my local hacker space if they hade an good microscope but they only got an older fix one, have not seen it.. so i have now my own microscope on the way and hope it will be here in 7 days time and then i can try do the hack you have done..

                                                                                                                                       

                                                                                                                                      I can see you only have split the VDD1V8CORE but what about the other VDD1V8ETH and VDD1V8USB ?

                                                                                                                                       

                                                                                                                                       

                                                                                                                                      Tooms

                                                                                                                                      • 65. Re: RG1 1.8v regulator
                                                                                                                                        Tooms

                                                                                                                                        selsinork wrote:

                                                                                                                                         

                                                                                                                                        My IR thermometer arrived yesterday

                                                                                                                                        I was looking at picking one up, but noticed that even rather expensive ones seem to have a minimum measurement 'spot' of something around 20mm which is rather larger than the lan9512. I was wondering just how that affects the readings..  Presumably they average the total emissions over whatever is in the sensors view somehow.

                                                                                                                                         

                                                                                                                                        Like you I don't have a Pi that runs as hot as some reports, and without one it's difficult to form a theory on what the cause is.

                                                                                                                                         

                                                                                                                                        yes the IR meter have there issues and you have to know it to get good readings and i have even an very good Fluke 568 there is on the high side of them and i dont use muchs because they crude in eletronics work and it is better to use an IR cam

                                                                                                                                         

                                                                                                                                        The Fluke 568 IR meter i am having is having and IR spot of (the number is is IR spot size and the distance from the surface)

                                                                                                                                        Spot 19mm @ 300mm distance

                                                                                                                                        Spot 18mm @ 900mm distance

                                                                                                                                        Spot 42mm @ 1500mm distance

                                                                                                                                         

                                                                                                                                        you also has to hold it at an right angle

                                                                                                                                         

                                                                                                                                         

                                                                                                                                        next time i will do some testing i will take both some IR images and use the IR meter and let you know what it is showing, but in the mean time try look at the images i have posted there is an graf showing the temparatura across the surface of the chip and you can clearly see the edges of the chip and that there is an very tinny hotsport at the center of the chip.

                                                                                                                                         

                                                                                                                                         

                                                                                                                                        Tooms

                                                                                                                                        • 66. Re: RG1 1.8v regulator

                                                                                                                                          it is better to use an IR cam

                                                                                                                                          I'd love one.. I looked at prices. No way can I afford one

                                                                                                                                           

                                                                                                                                          The Fluke 568 IR meter i am having

                                                                                                                                          Yeah, that's the one I was looking at, it was the only one I could find that gave a good explanation of the D:S relationship and that was what decided me not to bother getting one - my dodgy sensor stuck to the top center of the IC is likely more accurate

                                                                                                                                          • 67. Re: RG1 1.8v regulator
                                                                                                                                            PeteL

                                                                                                                                            Hi

                                                                                                                                             

                                                                                                                                            If it has a different signal name it is not connected to the 1V8 plane.  Like most good CAD systems it does 'mostly' what it's told.

                                                                                                                                             

                                                                                                                                            I've been travelling again and not been able to get to my lab but I'm now in 'full' duplex conversation with Microchip (ex:SMSC).

                                                                                                                                             

                                                                                                                                            I see the issue with 'higher' temp but now I get the feeling you are looking to fix something else with this mod?  Can you confirm?  There is mention of the USB issue - point me at it please and anything else you think is connected.

                                                                                                                                             

                                                                                                                                            Cheers

                                                                                                                                             

                                                                                                                                            Pete

                                                                                                                                            • 68. Re: RG1 1.8v regulator
                                                                                                                                              PeteL

                                                                                                                                              Has anyone found the emissivity coefficients that we should use for the encapsulant on the chip (0.92 has been suggested)?

                                                                                                                                               

                                                                                                                                              I've asked a few chip suppliers FAEs and been met with a blank stare!  I guess that's why I still use thermocouples, but they are messy as I always gunk them up with heatsink compound.

                                                                                                                                               

                                                                                                                                              Cheers

                                                                                                                                               

                                                                                                                                              Pete

                                                                                                                                              • 69. Re: RG1 1.8v regulator
                                                                                                                                                Tooms

                                                                                                                                                Hi

                                                                                                                                                 

                                                                                                                                                I am using the 0.95e on my Fluke 568 as this is the default one and it is for black plastic

                                                                                                                                                 

                                                                                                                                                the 568 build in tabel has:

                                                                                                                                                0.93 paint

                                                                                                                                                0.95 plastic

                                                                                                                                                0.93 water

                                                                                                                                                 

                                                                                                                                                an book i have about IR is having

                                                                                                                                                0.85 Brick, common

                                                                                                                                                0.94 Brick, refractory rough

                                                                                                                                                0.95 electrical tape black plastic

                                                                                                                                                0.92 Glass

                                                                                                                                                0.93 lacquer, bakelite

                                                                                                                                                0.94 paint average oil based

                                                                                                                                                0.94 paper black

                                                                                                                                                0.93 rubber

                                                                                                                                                0.92 tar paper

                                                                                                                                                 

                                                                                                                                                (I have only listed the values there seems usagbol to this as the list is alot longer..)

                                                                                                                                                 

                                                                                                                                                So based on this i will say around 0.93-0.95 so a good point will be 0.94e but as other users here is having IR meters and they are very likly fixed at 0.95e so i think it is best to use 0.95 so it is easyer to compire the results there is posted.

                                                                                                                                                 

                                                                                                                                                 

                                                                                                                                                Thomas

                                                                                                                                                • 70. Re: RG1 1.8v regulator
                                                                                                                                                  jamodio

                                                                                                                                                  coder27 wrote:

                                                                                                                                                   

                                                                                                                                                  Jamodio ought to be a hero on the RPi forum for finding what is probably

                                                                                                                                                  the most serious design error.  Instead, he is banned as a concern troll.

                                                                                                                                                   

                                                                                                                                                  I don't think I have to be considered a hero, somebody else would have noticed and reported the error(s) if RPF had released the schematics and Gerbers before sending the boards to production.

                                                                                                                                                   

                                                                                                                                                  There is another major issue with the quality of some of the components as I reported before. In particular the LDO voltage regulators that on the beta board were from NXP and now are from some Chinese knock off.

                                                                                                                                                   

                                                                                                                                                  In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

                                                                                                                                                   

                                                                                                                                                  To tell the truth this is not a complex board in number of parts, signals, nets, and we engineers often make errors, that's why when we work professionally we have a review process before we commit to large scale production. In this case the process didn't exist or some people were not paying attention.

                                                                                                                                                   

                                                                                                                                                  What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

                                                                                                                                                   

                                                                                                                                                  My .02

                                                                                                                                                  -J

                                                                                                                                                  • 71. Re: RG1 1.8v regulator
                                                                                                                                                    PeteL

                                                                                                                                                    Seems like a good suggestion - as you say at least we can compare results with some confidence, I think the issue on resolution, spot size is also a complicating factor.  From what I understand you will get the average of the spot size so any real hot spots will be averaged away.

                                                                                                                                                     

                                                                                                                                                    I've been trying to find a IR lens that will give 10mm x 15mm as the total field of view.  Interestingly it gets even more complicated when you look at effective touch temperature and we need a gizmo called a "thermesthesiometer probe" but these are not commercially available as far as I have found - if you find one let me know.

                                                                                                                                                     

                                                                                                                                                    NASA (slightly old but the most recent I could find) have suggested that 45C is tolerable (indefinitely) for polished metal with an effective infinite heat capacity, and obviously a very high thermal conductivity, but this does not play well to our circumstances unless we measure less than that.

                                                                                                                                                     

                                                                                                                                                    So I think there are three issue in this thread:

                                                                                                                                                     

                                                                                                                                                    1) Touch temperature concern.

                                                                                                                                                    2) Die temperature and effect on performance.

                                                                                                                                                    3) Effect on functionality of USB? (Circumstances yet to be determined)**.

                                                                                                                                                     

                                                                                                                                                    I have not seen any reports that making the suggested mod fixes anything, I'm sure you will let me know if I've missed it.

                                                                                                                                                     

                                                                                                                                                    As always - comments welcome.

                                                                                                                                                     

                                                                                                                                                    Cheers

                                                                                                                                                     

                                                                                                                                                    Pete

                                                                                                                                                    • 72. Re: RG1 1.8v regulator
                                                                                                                                                      In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

                                                                                                                                                      I must have replaced thousands of those in PC's, but that particular problem seems to be solved - at least from what I see.

                                                                                                                                                       

                                                                                                                                                      From the people I know who work for chinese manufacturers it certainly appears that a large part of going to china is to do with getting counterfeit parts - if not the whole device!

                                                                                                                                                      Part of the problem is quickly going to become - if it hasn't already - that your 'original' NXP LDO will have been made in the same factory, on the same equipment, and to the same design as the chinese one. Maybe both will use the NXP design, maybe the chinese one. As long as they're not totally flaky and outlast the warranty there's a part of me that thinks nobody will care - stuff dying sooner means you replace it sooner and someone makes another sale. The beancounters like that idea

                                                                                                                                                       

                                                                                                                                                      Have we all seen this before ?

                                                                                                                                                      chinese-capacitor.jpg

                                                                                                                                                      I have no idea if it's real or someone just did a mockup to illustrate a point, but certainly made me smile

                                                                                                                                                      • 73. Re: RG1 1.8v regulator
                                                                                                                                                        morgaine

                                                                                                                                                        jamodio wrote:

                                                                                                                                                         

                                                                                                                                                        What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

                                                                                                                                                         

                                                                                                                                                        +1.

                                                                                                                                                         

                                                                                                                                                        Feedback on issues is part of the engineering process.  That's alien to Liz's hype & fandom process.

                                                                                                                                                         

                                                                                                                                                        PeteL wrote:

                                                                                                                                                         

                                                                                                                                                        As always - comments welcome.

                                                                                                                                                         

                                                                                                                                                        +1

                                                                                                                                                         

                                                                                                                                                        I've been trying to quantify one particular area of faulty operation, RF mice on self-powered USB hubs .  With dozens of tested (device X hub) combinations, and all 8 of the data points for RF mice showing complete failure on Pi, it's a very black-and-white test bench for USB functionality.  I happen to have a hot-running LAN9512, so I may be able to provide relevant testing if the 1.8v issues are thought to couple to USB operation.

                                                                                                                                                         

                                                                                                                                                        Morgaine.

                                                                                                                                                        • 74. Re: RG1 1.8v regulator
                                                                                                                                                          PeteL

                                                                                                                                                          J

                                                                                                                                                           

                                                                                                                                                           

                                                                                                                                                          Connecting the two 1V8’s is a sub optimal piece of design (you can look that up in the engineering translation dictionary - starts with a 'c' ends in ‘up’), and I didn't think that was of debate.

                                                                                                                                                           

                                                                                                                                                           

                                                                                                                                                          The design did go through extensive review within the 'inner circle' of supporters who 'know' and have worked with the chips before especially the BCM. Both prototypes and pre-prototypes had this same connection and that of course made it more difficult. I also suspect, had there not been some reason to go and look, it would have never been identified. Just for the record, your technical input is appreciated, but rather than just implying - you could have just asked? Maybe you did earlier and I missed it.

                                                                                                                                                           

                                                                                                                                                           

                                                                                                                                                          We tried to do the best job possible with the limited support and resources that the early phase project had. (We were going to make 5000-10,000 beta boards max). None of the early stress testing revealed the issue and only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). Of the returns I have for analysis, I have still have not found a real ‘steamer’. These could be in part due to poor underfill or even a short/defect elsewhere on top of what we are asking the chip to do.

                                                                                                                                                           

                                                                                                                                                          There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later).

                                                                                                                                                           

                                                                                                                                                          It doesn't matter if you spend £1 or $10M things slip through, and there have been some very high profile events in that $10M category in all walks of engineering!

                                                                                                                                                           

                                                                                                                                                           

                                                                                                                                                          I remember saying at the outset that Pi would never be perfect - just doesn't happen in engineering there is always something to be optimised, improved. What we do need to do is measure, evaluate, garner input and decide what, if anything, needs to be done. And I do appreciate the work done by people on this thread already.

                                                                                                                                                           

                                                                                                                                                           

                                                                                                                                                          Pete

                                                                                                                                                           

                                                                                                                                                          • 75. Re: RG1 1.8v regulator
                                                                                                                                                            PeteL

                                                                                                                                                            Question is - were the Rubycon's real !

                                                                                                                                                             

                                                                                                                                                            P

                                                                                                                                                            • 76. Re: RG1 1.8v regulator

                                                                                                                                                              Pete,

                                                                                                                                                              You wrote:

                                                                                                                                                              "There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later)."

                                                                                                                                                               

                                                                                                                                                              I'm quite sure that there is no established connection at this point

                                                                                                                                                              between this 1.8v power issue and any USB or other functional problems.

                                                                                                                                                              Users with hot lan chips have been having USB problems, but so have

                                                                                                                                                              users with cooler lan chips, so the USB problems could very well be due to

                                                                                                                                                              other causes.

                                                                                                                                                               

                                                                                                                                                              SMSC has said "don't do that", but they haven't said what will happen

                                                                                                                                                              if you do.  We've seen pretty convincing evidence that the lan chip

                                                                                                                                                              will get hot, but don't know if it will malfunction, or cause a malfunction

                                                                                                                                                              on the other devices connected to 1.8v, or whether its expected lifetime

                                                                                                                                                              will be shortened.

                                                                                                                                                               

                                                                                                                                                              you wrote:

                                                                                                                                                              "only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). "

                                                                                                                                                               

                                                                                                                                                              I'm not sure what you are basing your statistics on.  Is it the return rate?

                                                                                                                                                              I suspect that the rate is higher than 0.01%.  If the rate was that low,

                                                                                                                                                              then certainly there would be no hesitation to announce that due to a

                                                                                                                                                              design defect, a very small number of boards have chips that run blisteringly

                                                                                                                                                              hot, and any user who is unlucky enough to have gotten one is welcome

                                                                                                                                                              to exchange it.

                                                                                                                                                               

                                                                                                                                                              you wrote:

                                                                                                                                                              "We tried to do the best job possible with the limited support and resources that the early phase project had."

                                                                                                                                                               

                                                                                                                                                              I don't think anyone would deny that you did a fantastic job with the limited

                                                                                                                                                              resources you had.  But I think jamodio's point is that releasing schematics

                                                                                                                                                              prior to production would not have cost anything, and could have resulted

                                                                                                                                                              in great savings by uncovering such errors before mass production.

                                                                                                                                                               

                                                                                                                                                              I am not a hardware guy, but I am quite surprised to see that hardware

                                                                                                                                                              schematics aren't clear about the direction of power flow.  It is a bit

                                                                                                                                                              ironic that the beta board had a string of decoupling capacitors that

                                                                                                                                                              should have been connected to 1.8v, but wasn't, and the production

                                                                                                                                                              board has a similar string of decoupling capacitors that shouldn't have

                                                                                                                                                              been connected to 1.8v, but was.  But there is nothing in the schematics

                                                                                                                                                              to show which pins on the ICs have power going in, and which have

                                                                                                                                                              power coming out.  So it is very difficult to check the schematics to

                                                                                                                                                              find these kinds of errors, where components are either not connected

                                                                                                                                                              to any source of power, or are connected to more than one source.

                                                                                                                                                               

                                                                                                                                                              At this point we are completely in the dark about what hardware revisions

                                                                                                                                                              are contemplated, other than Eben's mention of some unspecified pcb

                                                                                                                                                              change for FCC/CE residential compliance.  Hopefully that will change.

                                                                                                                                                               

                                                                                                                                                              Eben said he wanted to fix the FCC/CE issue prior to the educational

                                                                                                                                                              release.  Since the 2012/2013 school year is about to start, the timing

                                                                                                                                                              seems really odd not to have fixed that by now.  The timing also seems

                                                                                                                                                              really odd not to have published the user's manual by now.  Amazon is

                                                                                                                                                              showing a projected date of 16 October.  So are you aiming for the

                                                                                                                                                              2013/2014 school year?  If so, I'm quite sure you will need 512MB ram

                                                                                                                                                              to be competitive.

                                                                                                                                                              • 77. Re: RG1 1.8v regulator
                                                                                                                                                                jamodio

                                                                                                                                                                First of all thanks for being here and for following up. I really appreciate the work you have done and I truly believe that some of the mishaps from the RPF are not your own making.

                                                                                                                                                                 

                                                                                                                                                                Connecting the two 1V8’s is a sub optimal piece of design (you can look that up in the engineering translation dictionary - starts with a 'c' ends in ‘up’), and I didn't think that was of debate.

                                                                                                                                                                 

                                                                                                                                                                Well, you may call it "sub optimal design" but it is actually an error, and in my dictionary it starts with 'f' and ends in 'up' ;-)

                                                                                                                                                                 

                                                                                                                                                                 

                                                                                                                                                                The design did go through extensive review within the 'inner circle' of supporters who 'know' and have worked with the chips before especially the BCM. Both prototypes and pre-prototypes had this same connection and that of course made it more difficult. I also suspect, had there not been some reason to go and look, it would have never been identified. Just for the record, your technical input is appreciated, but rather than just implying - you could have just asked? Maybe you did earlier and I missed it.

                                                                                                                                                                 

                                                                                                                                                                Obviously the process didn't work, and as you clearly know in the previous prototype it was reported that various power connections were missing, kind of a surprise since part of the 'inner circle' was apparently involved in the design of the BCM SoC chip. Perhaps the 'inner circle' has a very small radius and some of the supporters actually "don't know." Not just me but many other asked while before the boards went to production for schematics/gerbers and the only we obtained was a crop showing a psu section. I reported the problem as soon as the schematics were made public, and it didn't took too much know how, just reading the SMSC datasheet to figure what each pin was used for, something that we don't even have for the SoC part.

                                                                                                                                                                 

                                                                                                                                                                And about asking, I asked what else is on "the list", no response yet.

                                                                                                                                                                 

                                                                                                                                                                  We tried to do the best job possible with the limited support and resources that the early phase project had. (We were going to make 5000-10,000 beta boards max). None of the early stress testing revealed the issue and only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). Of the returns I have for analysis, I have still have not found a real ‘steamer’. These could be in part due to poor underfill or even a short/defect elsewhere on top of what we are asking the chip to do.

                                                                                                                                                                 

                                                                                                                                                                The foundation should have put they arrogance away and ask for help and additional support, there has been a large group of people willing all the time to cooperate, and they are still out there but the RPF attitude has been always "what we did is perfect and we know everything." I'll not trust any number, percentages or analysis derived from them given that there are no public numbers about how many boards have been manufactured, how many have failed, how many have been sold. how many have been shipped, how many have been returned, etc, and there is no formal or reasonable system to track complains/failures/fixes.

                                                                                                                                                                 

                                                                                                                                                                There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later).

                                                                                                                                                                 

                                                                                                                                                                I'm not sure if there is a direct connection with several of the problems reported with USB. Certainly the entire power architecture does not help, but there are some hardware/firmware issues related to USB where things are not working as expected and somebody is now reading the Verilog files for that piece of silicon on the SoC discovering some limitations and other stuff hidden behind the obscurity of the drivers.

                                                                                                                                                                 

                                                                                                                                                                I know that everybody have tried to do their best, but recognition for a successful endeavour comes from producing positive results and not from the effort put to get them.

                                                                                                                                                                 

                                                                                                                                                                My .02

                                                                                                                                                                -J

                                                                                                                                                                • 78. Re: RG1 1.8v regulator
                                                                                                                                                                  PeteL

                                                                                                                                                                   

                                                                                                                                                                  So I guess it is not worth me publishing here what I know and what I can measure?

                                                                                                                                                                   

                                                                                                                                                                  I do take issue with your final comment - it has been a success so far - with some measure of "success failure" thrown in.

                                                                                                                                                                   

                                                                                                                                                                  I've been talking to users who just have one or two and are over the moon with them (faults issues and all) and they tell me that they have already learnt so much.

                                                                                                                                                                   

                                                                                                                                                                  My overall positive view may yet be proved wrong, but as I said right at the outset it isn’t perfect, never will be - we just have to remember why we are clearing the swamp!

                                                                                                                                                                   

                                                                                                                                                                  Off to watch the Olympics on TV

                                                                                                                                                                   

                                                                                                                                                                   

                                                                                                                                                                  Pete

                                                                                                                                                                  • 79. Re: RG1 1.8v regulator

                                                                                                                                                                    I am not a hardware guy, but I am quite surprised to see that hardware

                                                                                                                                                                    schematics aren't clear about the direction of power flow.

                                                                                                                                                                    In many years of working in the subcontract hardware assembly business I've seen hundreds of schematics from all sorts of companies, from the biggest names to tiny one man outfits and I've rarely seen anything indicating power direction.

                                                                                                                                                                    This sort of thing wouldn't have been a problem in years gone by as it was rare for IC's to have internal regulators and often power was supplied from an off board supply so it was obvious.

                                                                                                                                                                    Things change, technology gets more complex, leaving room for ambiguity and errors to creep in.

                                                                                                                                                                     

                                                                                                                                                                    IME Petes schematics are pretty good, they lack some things you'd normally find on much larger schematics like a cross reference of refdes and signals to page and location, but for four pages most of that stuff isn't really necessary.

                                                                                                                                                                    • 80. Re: RG1 1.8v regulator

                                                                                                                                                                      lol.. nope.. it's like one of those russian dolls you keep removing another layer until you get to the 0201 smt cap somewhere inside

                                                                                                                                                                      • 81. Re: RG1 1.8v regulator

                                                                                                                                                                        So I guess it is not worth me publishing here what I know and what I can measure?

                                                                                                                                                                         

                                                                                                                                                                        I'd certainly appreciate anything you're willing to share Pete

                                                                                                                                                                        • 82. Re: RG1 1.8v regulator
                                                                                                                                                                          John Beetem

                                                                                                                                                                          PeteL wrote:

                                                                                                                                                                           

                                                                                                                                                                           

                                                                                                                                                                           

                                                                                                                                                                          I remember saying at the outset that Pi would never be perfect - just doesn't happen in engineering there is always something to be optimised, improved.

                                                                                                                                                                          There is a story about a craftsman who made beaten copper doors for the Tsar of Russia's throne room.  He would take a large sheet of copper and beat it over and over with a hammer, creating beautiful swirling patterns.  Someone asked him "how do you know when you're done?"  He answered: "It's never done.  I just keep hitting it until they take it away from me."

                                                                                                                                                                           

                                                                                                                                                                          Engineering is like that -- especially software engineering.

                                                                                                                                                                           

                                                                                                                                                                          Thank you for being open to suggestions, Pete!

                                                                                                                                                                          • 83. Re: RG1 1.8v regulator

                                                                                                                                                                            Pete,

                                                                                                                                                                            >So I guess it is not worth me publishing here what I know and what I can measure?

                                                                                                                                                                             

                                                                                                                                                                            You are being way too defensive.  Nobody is blaming you for the design error.

                                                                                                                                                                            If I understand your earlier comment correctly, the error was copied from the

                                                                                                                                                                            alpha board that you didn't design yourself.  And I don't think it matters much

                                                                                                                                                                            to hear that you have found a happy customer.  On this forum and the RPi

                                                                                                                                                                            forum, happy customers are hugely outnumbered, not that that matters either.

                                                                                                                                                                             

                                                                                                                                                                            It would be very nice for you to publish what you know and what you

                                                                                                                                                                            can measure.  However, regardless of what further information you can

                                                                                                                                                                            provide, I think it is clear enough at this point that the lan chip is not

                                                                                                                                                                            supposed to be blisteringly hot, as people have been complaining about

                                                                                                                                                                            in vain for months, and it is essential to promptly tell those customers what

                                                                                                                                                                            their remedy is, rather than what they have been told so far, which is that

                                                                                                                                                                            hot chips are normal in PCs.

                                                                                                                                                                             

                                                                                                                                                                            Going forward it is clear enough that the foundation has limited resources

                                                                                                                                                                            for debugging their hardware and software, and would greatly benefit from

                                                                                                                                                                            a bit more openness with regard to schematics, and a bit more cooperation

                                                                                                                                                                            with those who point out problems.

                                                                                                                                                                            • 84. Re: RG1 1.8v regulator
                                                                                                                                                                              tmackay

                                                                                                                                                                              Hi Pete,

                                                                                                                                                                              PeteL wrote:

                                                                                                                                                                               

                                                                                                                                                                              I see the issue with 'higher' temp but now I get the feeling you are looking to fix something else with this mod?  Can you confirm?  There is mention of the USB issue - point me at it please and anything else you think is connected.

                                                                                                                                                                              I'm a big fan of reliability and uptime, after a few kernel panics I was hoping that this might help with stability, it didn't seem to though. Still worth a try. I can trigger a kernel panic by using nfs pretty reliably. Software upgrades seem to have helped significantly, and development is ongoing. It is a pretty harsh test, blasting udp packets from a gigabit nic to the Pi with all error correction done in software. I've since not been able to get it to crash repeatably with other (more polite) tcp based protocols.

                                                                                                                                                                               

                                                                                                                                                                              I'm also interested in increasing power efficiency, as I plan to build battery powered robots and data loggers.

                                                                                                                                                                               

                                                                                                                                                                              So no, I personally don't have a specific hardware issue.

                                                                                                                                                                              • 85. Re: RG1 1.8v regulator
                                                                                                                                                                                tmackay

                                                                                                                                                                                The more I think about it, I think I like Tooms idea better. By replacing the 1.8V reg with a slightly higher switcher, you have the added benefit of bypassing the internal linear regulator of IC3 and saving even more power. It has been stated that the LAN chip was not indended to be driven from these pins, but I don't think that's going to be any worse than the current situation. It obviously "works" in this configuration.

                                                                                                                                                                                (edit) If only the 1.8V rail was exposed on the GPIO this power saving "feature" could be a plug-in solution. They really are quite clever, the other SMSC chips with documented "internal regulator disable mode" probably cost more. How's that for spin?

                                                                                                                                                                                • 86. Re: RG1 1.8v regulator

                                                                                                                                                                                  This sort of thing wouldn't have been a problem in years gone by as it was rare for IC's to have internal regulators and often power was supplied from an off board supply so it was obvious. Things change, technology gets more complex, leaving room for ambiguity and errors to creep in.

                                                                                                                                                                                   

                                                                                                                                                                                  Selsinork,

                                                                                                                                                                                    Thanks for the explanation.  It makes sense. 

                                                                                                                                                                                  Here I've assumed that at least since Intel's fdiv bug, hardware

                                                                                                                                                                                  guys have had the advantage over software guys because they

                                                                                                                                                                                  use mostly formal verification techniques where we rely mostly

                                                                                                                                                                                  on ad hoc testing.

                                                                                                                                                                                    I couldn't figure out at first why it was difficult to verify that

                                                                                                                                                                                  all the components on the RPi board were properly connected

                                                                                                                                                                                  to power, which I assumed to be a pretty fundamental property

                                                                                                                                                                                  to be sure was verified, until I saw that power flow isn't

                                                                                                                                                                                  specified on the schematics.

                                                                                                                                                                                    It makes one wonder what is meant by the claims that the RPi

                                                                                                                                                                                  design was carefully checked.  How can you check something

                                                                                                                                                                                  that isn't specified, especially when the datasheets for the ICs

                                                                                                                                                                                  are either non-existent or ambiguous themselves?

                                                                                                                                                                                    As technology gets more complex, ambiguity has to be reduced

                                                                                                                                                                                  so checking can be increased, just to keep reliability from getting worse.

                                                                                                                                                                                  • 87. Re: RG1 1.8v regulator
                                                                                                                                                                                    morgaine

                                                                                                                                                                                    The engineering process after initial release is about identifying existing shortcomings and evaluating alternative solutions for future releases, and doing this iteratively for each new version or model.  It is not about pointing fingers at engineers (which is completely irrelevant and unhelpful), and it is not about those engineers reacting defensively when problems are identified.

                                                                                                                                                                                     

                                                                                                                                                                                    Reacting defensively makes it hard to analyse technical problems because it personalizes them, and when the defensive reaction is as extreme as on the Foundation forums and leads to messengers being banned, the engineering process is completely stillborn.  We're free of the latter here, but please let's remain free of the former as well.

                                                                                                                                                                                     

                                                                                                                                                                                    PeteL wrote:

                                                                                                                                                                                     

                                                                                                                                                                                    I do take issue with your final comment - it has been a success so far - with some measure of "success failure" thrown in.

                                                                                                                                                                                     

                                                                                                                                                                                    Pi Model B is most definitely not an engineering success.  Engineering success is a fairly measureable quantity related to how much of the engineering involved was actually successful, ie. how much of the product works as expected.  (And "success failure" is not a term any engineer should ever utter.)

                                                                                                                                                                                     

                                                                                                                                                                                    If any other computing device had been found to have such a catalogue of compatibility problems when used with totally class-compliant USB devices, it is highly likely that it would have been recalled immediately and withdrawn from sales pending redesign.  The Pi is setting an example of USB incompatibility such as has not been seen since the first year of release of the USB spec and initial devices.

                                                                                                                                                                                     

                                                                                                                                                                                    These USB problems appear to be in part fallout from least-cost BCM2835 SoC design and its USB  driver, and in part a consequence of excessively restrictive power design, but the board is a unit and its USB functionality is an extremely important part of its operation.  That key functionality has major faults.  It is not an engineering success (the only kind that concerns us here), because it is failing to operate as expected, and there are countless examples of how it is failing spread across the planet and reported on both RPF and Element 14 forums.

                                                                                                                                                                                     

                                                                                                                                                                                    I'm going to assume that the objectively incontrovertible fact of widespread failures is accepted, because anything else would not be a professional engineering response given the evidence.  The big task then becomes to identify the reasons and find solutions, and that is why we are here, in my opinion.

                                                                                                                                                                                     

                                                                                                                                                                                    Unless we can get past acceptance of the problems though, there is little prospect of finding solutions.

                                                                                                                                                                                     

                                                                                                                                                                                    Regarding how the 1.8V design might affect LAN9512 operation, I have no evidence that they are related either, but I am just hoping that they are related in some way that we cannot currently see because otherwise it seems likely that the Pi's huge USB faults are with us to stay.

                                                                                                                                                                                     

                                                                                                                                                                                    Morgaine.

                                                                                                                                                                                    • 88. Re: RG1 1.8v regulator
                                                                                                                                                                                      jamodio

                                                                                                                                                                                      Pete anything you are able and wish to share will be very valuable, I can say that so far I've not seen anything being shared yet...

                                                                                                                                                                                       

                                                                                                                                                                                      I don't feel qualified to state if the mission of RPF has been or will be a success or not, my comment was referred to situations where people say "we tried hard," "we did our best."

                                                                                                                                                                                       

                                                                                                                                                                                      Nobody will deny to acknowledge and appreciate the efforts but what it counts at the end are results.

                                                                                                                                                                                       

                                                                                                                                                                                      At one time I had over 100 engineers working in my team and I never accepted that something that was accomplished by "doing their best" couldn't be done better and more efficiently, because as others said engineering is a cumulative process where we constantly learn and apply the new knowledge to do things better, and more efficient, and which will never be perfect.

                                                                                                                                                                                       

                                                                                                                                                                                      I'm not a fanboi or a detractor of the R-pi, I still consider that it was a great idea and something worth to create, I'm not angry and I'm still using the 2 boards I purchased and planning to still work on some projects with them, now would I recommend it to local schools?, the answer at this time is NO.

                                                                                                                                                                                       

                                                                                                                                                                                      BTW kudos to the UK and London for putting such a great 2012 Olympics.

                                                                                                                                                                                       

                                                                                                                                                                                      Regards

                                                                                                                                                                                      Jorge

                                                                                                                                                                                      • 89. Re: RG1 1.8v regulator
                                                                                                                                                                                        morgaine

                                                                                                                                                                                        Everyone doing their best is assumed.  It has no bearing on whether a product works or not, except possibly if the testers are ineffective and hence undermine everyone else on a project.  If anyone else in an engineering team fails, it should be caught at test to within certain limits (not 100%).

                                                                                                                                                                                         

                                                                                                                                                                                        But more importantly and relevantly, that issue is not part of the engineering process.  That process at the core of our profession concerns the objects being engineered, not the people.

                                                                                                                                                                                        • 90. Re: RG1 1.8v regulator

                                                                                                                                                                                          Here I've assumed that at least since Intel's fdiv bug, hardware

                                                                                                                                                                                          guys have had the advantage over software guys because they

                                                                                                                                                                                          use mostly formal verification techniques where we rely mostly

                                                                                                                                                                                          on ad hoc testing.

                                                                                                                                                                                          Don't get me wrong, formal verification has it's place and can help a lot. It also leads to two sometimes difficult problems

                                                                                                                                                                                          1. a simple error early in the design or even in a symbol/footprint supplied by a third party gets propagated through the design resulting in something that may not function at all, or as in this case works but is suboptimal. As the verification passes everyone has a high sense of confidence it'll work.
                                                                                                                                                                                          2. Over time it leads to a reliance of the verification technology and a de-skilling of the job - beancounters strike again.

                                                                                                                                                                                          In short there's no substitute for knowledge and experience. Experience of making the stupid mistakes and fixing them usually helps a lot.

                                                                                                                                                                                           

                                                                                                                                                                                          If you're a software person, you're probably familiar with unit testing.  IME it suffers from variants of the same problems.

                                                                                                                                                                                          1. The spec is wrong, unit test to the letter of the spec and the result is wrong, but the test passes.
                                                                                                                                                                                          2. Often the person who writes the code also writes the unit test for it, if they have some misunderstanding of the requirement, the test will pass but the result is still wrong.

                                                                                                                                                                                          The same observation that there's no substitute for knowledge and experience holds for software just as much as for hardware.

                                                                                                                                                                                           

                                                                                                                                                                                          A dodgy datasheet, or software spec, just means it's even harder to spot the error.

                                                                                                                                                                                           

                                                                                                                                                                                          Hardware people do ad-hoc testing too, the tools are different and we literally get our fingers burnt - with a soldering iron

                                                                                                                                                                                           

                                                                                                                                                                                            As technology gets more complex, ambiguity has to be reduced

                                                                                                                                                                                          so checking can be increased, just to keep reliability from getting worse.

                                                                                                                                                                                          Agree, but as the complexity grows you're increasingly faced with a datasheet being 1000 pages instead of 50. It's trying to reduce ambiguity, but it's bringing up the needle in a haystack problem.

                                                                                                                                                                                          Then there's always the problem where increasing complexity gives you 17 different ways to do something, none of them obviously better or worse.

                                                                                                                                                                                          • 91. Re: RG1 1.8v regulator
                                                                                                                                                                                            morgaine

                                                                                                                                                                                            Since we're talking about testing now, and looking for ways to improve future versions of Pi, let's focus on that a bit since it's clear that testing needs to be revamped to a significant degree.  This observation stems from the fact that testing somehow managed to miss the dramatically widespread incompatibility with common class-compliant USB devices that users have encountered and reported, as well as not catching any USB event or data loss, nor the high operating temperature of some LAN9512 devices.

                                                                                                                                                                                             

                                                                                                                                                                                            It seems that USB testing fell short in several respects:

                                                                                                                                                                                             

                                                                                                                                                                                            • Sample size.  Even if devices had been chosen at random, with a sufficient sample size it should have become apparent that there is a large incompatibility problem and that data loss is common.
                                                                                                                                                                                            • Breath of devices tested.  Within the range of devices that fall within Pi's intended application area, a representative selection of device types and most common brands would have raised confidence that Pi works correctly with normal class-compliant devices that use only the generic drivers for their class.  It is very clear that Pi does not.
                                                                                                                                                                                            • Depth of functional testing.  This refers to performance, overhead and error rate characterisation.  USB supports various different types of data transfer, but the most common and important types are lossless, ie. these USB transfers are meant to be 100% reliable.  Users have found that USB data loss from mouse and keyboard are common, but this is hard for users to quantify.  Given the importance of these HID devices, the error rate should have been characterised at testing time.
                                                                                                                                                                                            • Physical tests.  Although only laterally related to USB testing, the wide variation in LAN9512 operating temperatures was not caught during Pi testing.  This suggests that either the test sample size was not large enough to reveal the problem or that it wasn't conceived that temperature measurement should be added to the set of tests that were performed.

                                                                                                                                                                                             

                                                                                                                                                                                            Everything is a trade-off, and perfection can never be reached through testing.  However, basic correct operation is non-negotiable, so enough testing needs to be performed to guarantee that each of these categories are covered to a satisfactory degree.  That is the only way to have measureable confidence of engineering success upon product release.

                                                                                                                                                                                             

                                                                                                                                                                                            Assuming that the premise is agreed, we then have to come up with a way to achieve this within cost and time constraints.  It has to be agreed first though.

                                                                                                                                                                                             

                                                                                                                                                                                            Morgaine.

                                                                                                                                                                                            • 92. Re: RG1 1.8v regulator
                                                                                                                                                                                              John Beetem

                                                                                                                                                                                              selsinork wrote:

                                                                                                                                                                                               

                                                                                                                                                                                              If you're a software person, you're probably familiar with unit testing.  IME it suffers from variants of the same problems.

                                                                                                                                                                                              1. The spec is wrong, unit test to the letter of the spec and the result is wrong, but the test passes.
                                                                                                                                                                                              2. Often the person who writes the code also writes the unit test for it, if they have some misunderstanding of the requirement, the test will pass but the result is still wrong.

                                                                                                                                                                                              Expanding on (2), IMO you should always have different people designing and testing.  A good designer wants to make something work, a good tester wants to break it.  Getting both mind-sets in one person is a rarity, and inevitably leads to a conflict of interest.  Also, humans have difficulty perceiving what's really there versus what they want to see -- you should have someone else proofread your writing, and review your designs.

                                                                                                                                                                                              selsinork wrote:

                                                                                                                                                                                               

                                                                                                                                                                                              Agree, but as the complexity grows you're increasingly faced with a datasheet being 1000 pages instead of 50. It's trying to reduce ambiguity, but it's bringing up the needle in a haystack problem.

                                                                                                                                                                                              There are good and bad tech reference manuals out there.  It all depends on whether the vendor sees a manual as (1) a way to get more design wins and require less tech support, or (2) an painful burden to be dispatched as cheaply as possible.  A 1000-page TRM isn't a problem if it's well-organized -- I can just print the chapters I need for my particular application.  Many SoCs have all sorts of functions that I don't need, so I can just ignore them provided that the SoC is well designed and there aren't unexpected interactions.  OTOH, some 3000-page TRMs are that way because the writer copied and pasted identical functions and then made small changes to each copy instead of thinking out clearly what would be most helpful to the designer and making one copy with a table of individual differences.

                                                                                                                                                                                               

                                                                                                                                                                                              When a manufacturer is dodgy about documentation, it makes me wonder how well their products are designed, since a well-designed product generally starts with a well-written specification, which then provides the basis for a well-written TRM which doesn't cost much to complete.

                                                                                                                                                                                              • 93. Re: RG1 1.8v regulator
                                                                                                                                                                                                morgaine

                                                                                                                                                                                                John Beetem wrote:

                                                                                                                                                                                                 

                                                                                                                                                                                                When a manufacturer is dodgy about documentation, it makes me wonder how well their products are designed, since a well-designed product generally starts with a well-written specification, which then provides the basis for a well-written TRM which doesn't cost much to complete.

                                                                                                                                                                                                 

                                                                                                                                                                                                A TRM is written as much for the manufacturer's own staff as for the external audience.  If a company can't be bothered to describe to its own staff how its product works, it doesn't inspire any confidence that its staff actually knows how it works, so you can expect support and the company's support products to be poor or non-existent.

                                                                                                                                                                                                 

                                                                                                                                                                                                Orthogonal to the above, the days of monolithic TRMs or other large specification documents should have disappeared long ago.  Scalability refers not only to systems but to documentation as well.  Any non-trivial document needs to be hierarchical, distributed, and revisioned at each level of hierarchy, or it has no hope of being maintained to track the thing it describes.  Unfortunately today's prefered format for technical specs favours monolithic documentation.

                                                                                                                                                                                                • 94. Re: RG1 1.8v regulator
                                                                                                                                                                                                  Roger Wolff

                                                                                                                                                                                                  Even if the delivery is "monolithic", internally inside the company the separation should take place.


                                                                                                                                                                                                  With "monolithic delivery" I mean: "A single datasheet that describes the whole chip".

                                                                                                                                                                                                   

                                                                                                                                                                                                  With separation I mean that the different chapters are maintained and written separately.

                                                                                                                                                                                                   

                                                                                                                                                                                                  Care must be applied to ensure that when a module is functionally upgraded, the datasheets for the previous versions of that module don't get more complicated.

                                                                                                                                                                                                  • 95. Re: RG1 1.8v regulator
                                                                                                                                                                                                    Roger Wolff

                                                                                                                                                                                                    Having now read the last few pages of this thread....


                                                                                                                                                                                                    The LAN chip is not designed to deliver power on the 1.8V. To stick to the specs the two signals need to be decoupled. i.e. a PCB redesign.

                                                                                                                                                                                                     

                                                                                                                                                                                                    In practise the draw on the 1.8V is about 100mA. This means 3.3V-1.8V * 100mA = 150mW of power moves from the LAN chip to the regulator.

                                                                                                                                                                                                     

                                                                                                                                                                                                    In practise, on the total power-draw of almost a Watt, the lan chip will be able to handle the 1/6th of a watt extra power. Maybe not over the full temperature range, so stuffing the 'pi into a mostly-closed enclosure may lead to unneccessary problems.

                                                                                                                                                                                                     

                                                                                                                                                                                                    No recall of existing 'pi boards needs to be done. As said: The lan chip can handle it in practise, it is a question of conforming to the specifications, and being more robust.

                                                                                                                                                                                                     


                                                                                                                                                                                                    If you are comfortable with using chips outside the official specifications, you can save a bit of cost if you leave off RG1. As it seems to work with RG1 removed, or with RG1 there is little current flowing from it. The lan chip seems to be able to cope.

                                                                                                                                                                                                     

                                                                                                                                                                                                    Some people are expressing views that paralleled regulators will have one delivering ALL the current, and the other one none. This is not always the case, This would be the case if they are both ideal voltage sources (with an ideal diode in series). However in practise, both regulators would have a measureable output impedance. So if regulator 1 delivers 1.85V with an impedance of 1 ohm, and the other delivers 1.80V with an impedance of 0.1ohm, the first 50mA will be mostly delivered by the first regulator, but increasing the current draw to 100mA, the second regulator will provide about 50mA of that.

                                                                                                                                                                                                    • 96. Re: RG1 1.8v regulator
                                                                                                                                                                                                      Quiet_Flyer

                                                                                                                                                                                                      Roger Wolff wrote:

                                                                                                                                                                                                       

                                                                                                                                                                                                      Some people are expressing views that paralleled regulators will have one delivering ALL the current, and the other one none. This is not always the case, This would be the case if they are both ideal voltage sources (with an ideal diode in series). However in practise, both regulators would have a measureable output impedance. So if regulator 1 delivers 1.85V with an impedance of 1 ohm, and the other delivers 1.80V with an impedance of 0.1ohm, the first 50mA will be mostly delivered by the first regulator, but increasing the current draw to 100mA, the second regulator will provide about 50mA of that.

                                                                                                                                                                                                      The thing is, that isn't how regulators work, they aren't a voltage source with a resistive output.

                                                                                                                                                                                                       

                                                                                                                                                                                                      Regulators, including the two linear regulators we're dealing with here pretty much always consist of a voltage reference with a feedback circuit controlling a variable resistance between the input power pin and the output power pin provided by either a FET or a bipolar transistor. If the voltage on the output pin is above the reference voltage by more than a tiny amount then the feedback circuit will shut off the output transistor and nearly all the power will be provided by the device with the higher reference voltage. Where it gets funny is when the two reference voltages are very close, both regulators provide part of the power and you can get into oscillations and all sorts of fun and games depending on the impedances around the circuit.

                                                                                                                                                                                                      • 97. Re: RG1 1.8v regulator

                                                                                                                                                                                                        A TRM is written as much for the manufacturer's own staff as for the external audience.  If a company can't be bothered to describe to its own staff how its product works, it doesn't inspire any confidence that its staff actually knows how it works, so you can expect support and the company's support products to be poor or non-existent.

                                                                                                                                                                                                        You've not worked at any of the places I have then

                                                                                                                                                                                                         

                                                                                                                                                                                                        Reality tends to be that there'll be a warts-and-all document that only the design team in question will have access to. Someone will get tasked to produce a tidied up version which will then get sent to a dedicated team of technical writers who have no real knowledge of the device and somewhere in that loop it'll go to the lawyers before any sort of document can be made available internally, never mind publicly.

                                                                                                                                                                                                        You'll also probably have four levels of document, publicly available, available after signing NDA, internally available and design team warts-and-all. So how much substance remains in the public doc ?

                                                                                                                                                                                                        It's also highly likely they'll have some sort of records retention policy to make sure anything that could potentially be requested for a court case gets deleted ASAP.

                                                                                                                                                                                                         

                                                                                                                                                                                                        IMHO, the lawyers probably have more input to the public doc than the design team does!

                                                                                                                                                                                                         

                                                                                                                                                                                                        It might be nice to live in an ideal world where everything was done properly, the world we actually live in is more about protecting IP and maximising shareholder profit. In the eyes of the business people that means something completely different to what the engineers want.

                                                                                                                                                                                                         

                                                                                                                                                                                                        To give you an idea, I've worked places where even employees use google to find the docs. Says a lot about the internal organisation..

                                                                                                                                                                                                        • 98. Re: RG1 1.8v regulator
                                                                                                                                                                                                          Quiet_Flyer

                                                                                                                                                                                                          It gets better, you'll probably find that nobody at SMSC/Microchip will know what the actual capabilities of the in-built regulator are. Their chip designers won't have designed a regulator from the bottom up, they will have included a regulator from a design library, it will have been specified to have a little bit of headroom over what the LAN9512 requires for its own operation. Beyond that we're into "experimental" territory.

                                                                                                                                                                                                          • 99. Re: RG1 1.8v regulator
                                                                                                                                                                                                            Roger Wolff

                                                                                                                                                                                                            Andrew Warbrick wrote:

                                                                                                                                                                                                            Regulators, including the two linear regulators we're dealing with here pretty much always consist of a voltage reference with a feedback circuit controlling a variable resistance between the input power pin and the output power pin provided by either a FET or a bipolar transistor. If the voltage on the output pin is above the reference voltage by more than a tiny amount then the feedback circuit will shut off the output transistor and nearly all the power will be provided by the device with the higher reference voltage. Where it gets funny is when the two reference voltages are very close, both regulators provide part of the power and you can get into oscillations and all sorts of fun and games depending on the impedances around the circuit.

                                                                                                                                                                                                            Mostly correct.

                                                                                                                                                                                                             

                                                                                                                                                                                                            But if that "tiny amount" is very very small, or equivalently the gain in that feedback circuit is very large, then even with just ONE regulator, the result will be oscilations. So that's why 1) They don't design for inifinite gain in that stage 2) they specify that (usually 100nF) capacitor near the regulator to stabilize the output.

                                                                                                                                                                                                             

                                                                                                                                                                                                            So, as the voltage on the output drops due to increasing load, the difference between the reference voltage and the feedback voltage increases and the output transistor is driven more and more (to a lower resistance as you say).

                                                                                                                                                                                                             

                                                                                                                                                                                                            The end result is that you can measure a real output resistance on regulators.

                                                                                                                                                                                                            • 100. Re: RG1 1.8v regulator
                                                                                                                                                                                                              Quiet_Flyer

                                                                                                                                                                                                              You're absolutely right, but the point I was making is that actually pretty small differences in reference voltage result in one regulator of two connected in parallel providing nearly all the current. Yes, the gain in the feedback circuit isn't infinite but it's high enough that you don't need much difference in the outputs for one regulator to be doing nearly all the work. I won't pick nits over the semantics of resistance versus output impedance, you're right, the output does look like a resistor for small changes in load.

                                                                                                                                                                                                              • 101. Re: RG1 1.8v regulator
                                                                                                                                                                                                                jamodio

                                                                                                                                                                                                                I think I already said it a couple of times, that connection to the 1V8 power plane is an ERROR, that needs to be fixed.

                                                                                                                                                                                                                 

                                                                                                                                                                                                                The default action from RPF/Distributors for existing users would probably be "screw them", but that problem and the others (again where is the list?) must be fixed to stop screwing new users.

                                                                                                                                                                                                                 

                                                                                                                                                                                                                You can theorize and overanalyze what should happen if you put some extra load on those pins, well, if a car wasn't designed to fly, don't insist making it fly...

                                                                                                                                                                                                                 

                                                                                                                                                                                                                Connecting LDOs in parallel could lead to very nasty side effects, including oscillation, no proper regulation, decreased output voltage, noise incjection into the core, etc, etc, etc.

                                                                                                                                                                                                                 

                                                                                                                                                                                                                About the USB issues, besides what are probably limitations and problems with the actual module inside the SoC and its drivers, until you fix the issues with power and how it is delivered to USB devices, will be hard to do many tests with various devices, it will be just an empirical list of what things work and what apparently don't. I can tell you by a fact that without removing the polyfuses I had a very hard time to make anything wireless work.

                                                                                                                                                                                                                 

                                                                                                                                                                                                                -J

                                                                                                                                                                                                                • 102. Re: RG1 1.8v regulator
                                                                                                                                                                                                                  John Beetem

                                                                                                                                                                                                                  selsinork wrote:

                                                                                                                                                                                                                   

                                                                                                                                                                                                                  It's also highly likely they'll have some sort of records retention policy to make sure anything that could potentially be requested for a court case gets deleted ASAP.

                                                                                                                                                                                                                  When I hear the phrase "records retention policy", I immediately think of this Dilbert: http://dilbert.com/strips/comic/2004-03-22/.  I expect that arbitrarily-imposed records retention policies, especially automatic deletion of old e-mail, will result in some large firms collapsing as vital information is no longer available.  However, this will help small firms who have the luxury (and necessity) of being sensible.

                                                                                                                                                                                                                  selsinork wrote:

                                                                                                                                                                                                                   

                                                                                                                                                                                                                  It might be nice to live in an ideal world where everything was done properly, the world we actually live in is more about protecting IP and maximising shareholder profit. In the eyes of the business people that means something completely different to what the engineers want.

                                                                                                                                                                                                                  I completely agree with selsinork's comments above, but I'd like to point out to semiconductor manufacturers, their lawyers, and their bean counters that the way to maximize shareholder profit is to sell as many chips as possible, and withholding documentation means that engineers cannot include your chips in their products, or if they do, it will be ever so much harder to get those products working because of a lack of information.  You will not get any revenue from products that fail because good software could not be developed in time because of a lack of documentation.  If you're worried about lawsuits, tell your politicians to change the laws so that you can spend your revenue on product design instead of lawsuits.  Politicians will listen to you because you have deep pockets.

                                                                                                                                                                                                                  • 103. Re: RG1 1.8v regulator
                                                                                                                                                                                                                    Roger Wolff

                                                                                                                                                                                                                    There are several reasons to keep documentation hidden:

                                                                                                                                                                                                                    • Keep track of who has documentation, so that you can notify them when an "erratum" is found.
                                                                                                                                                                                                                    • Keep the documentation from view from competitors. Knowing the exact "API" eases copying.
                                                                                                                                                                                                                    • Keep track who wants to implement things with your chip. It might be useful to send a salesguy over when <somebigcompany> is considering using your chip. (which you know because they requested the docs for that chip).

                                                                                                                                                                                                                     

                                                                                                                                                                                                                    And when you can't find docs for a chip that you want to use in your hobby project, you have to realize that selling ONE more chip is not what they are after. Even if you manage to convince 9 of 99  friends to duplicate your project.

                                                                                                                                                                                                                     

                                                                                                                                                                                                                    I'm not saying that I agree with these things, but knowing WHY they might have these policies helps in finding strategies to change them.

                                                                                                                                                                                                                    • 104. Re: RG1 1.8v regulator
                                                                                                                                                                                                                      morgaine

                                                                                                                                                                                                                      jamodio wrote:

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      You can theorize and overanalyze what should happen if you put some extra load on those pins, well, if a car wasn't designed to fly, don't insist making it fly...

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      +1

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      There's a reason why engineers devise circuit blocks like LDOs, both conceptual and implemented, and the reason is so that you can black-box functionality and hence ride on the shoulders of giants, instead of crawling along on the ground reinventing everything.  If you break a black box, the giant evaporates and you land on your ass.

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      Connecting two LDOs in parallel has that effect.  All bets are off.

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      Fortunately, it doesn't need discussing, as Pete acknowledges the issue.  The only question is what happens now.  As usual RPF is completely opaque on that.

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      Morgaine.

                                                                                                                                                                                                                      • 105. Re: RG1 1.8v regulator

                                                                                                                                                                                                                        There are several reasons to keep documentation hidden:

                                                                                                                                                                                                                        • Part of the design isn't yours and you simply don't have the rights to release any docs.

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        As a couple of others have commented, various bits probably got bought-in or imported from a design library. So you may not have the docs or may be contractually bound not to disclose them. I'd take a guess that there's all sorts of stuff like that for the reasons Morgaine mentions - and it all comes back to money. Why employ an engineer who understands the inner workings of an LDO when you can simply buy in a cheap design pattern with no knowledge required.

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        It's not like I'm any different, I'll happily use a chip when I have no real idea how it works as long as there's just enough docs to let me accomplish my goal.

                                                                                                                                                                                                                        • 106. Re: RG1 1.8v regulator
                                                                                                                                                                                                                          morgaine

                                                                                                                                                                                                                          Using black boxes is good, not bad!  Without it we'd still be scratching on cave walls instead of landing 1-ton rovers on Mars.  But those black boxes must be respected, and not compromized by using them out-of-spec.

                                                                                                                                                                                                                           

                                                                                                                                                                                                                          The giants can evaporate very easily.

                                                                                                                                                                                                                          • 107. Re: RG1 1.8v regulator

                                                                                                                                                                                                                            The giants can evaporate very easily.

                                                                                                                                                                                                                            Yes, and that's a risk that never seems to get factored in.  Sooner or later the original designers of the black box have left the company, died, and the knowledge has been lost.

                                                                                                                                                                                                                             

                                                                                                                                                                                                                            What's then the cost to re-engineer that black box from zero when other reasons demand a change of spec ?

                                                                                                                                                                                                                            • 108. Re: RG1 1.8v regulator
                                                                                                                                                                                                                              morgaine

                                                                                                                                                                                                                              selsinork wrote:

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              The giants can evaporate very easily.

                                                                                                                                                                                                                              Yes, and that's a risk that never seems to get factored in.  Sooner or later the original designers of the black box have left the company, died, and the knowledge has been lost.

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              The answer is very simple, yet it is almost always dismissed out of hand by those who look only inwards and lack a global perspective:

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              Mankind's advances need to be fully open, so that nothing is lost.  Period.

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              The amount of wasted effort today is just beyond comprehension, as people compete instead of cooperate.  I don't know how one could even begin to quantify the waste, but I very much doubt that more than 1% of Mankind's effort is retained over time and leads to the advance of civilization.  More likely it's 0.001%.  Certainly the vast bulk of all commercial software effort is totally lost to humanity, all those millions of man-years down the drain as soon as software is EOL'd.

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              It's very sad when you sit back and think about it philosophically.  Technical progress could be running thousands or millions of times as fast as it is today if the fruits of all effort were open rather than zealously protected and then lost.  It's scary to think where we would be today.

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              Morgaine.

                                                                                                                                                                                                                              • 109. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                John Beetem

                                                                                                                                                                                                                                Morgaine Dinova wrote:

                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                The amount of wasted effort today is just beyond comprehension, as people compete instead of cooperate.  I don't know how one could even begin to quantify the waste, but I very much doubt that more than 1% of Mankind's effort is retained over time and leads to the advance of civilization.  More likely it's 0.001%.  Certainly the vast bulk of all commercial software effort is totally lost to humanity, all those millions of man-years down the drain as soon as software is EOL'd.

                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                It's very sad when you sit back and think about it philosophically.  Technical progress could be running thousands or millions of times as fast as it is today if the fruits of all effort were open rather than zealously protected and then lost.  It's scary to think where we would be today.

                                                                                                                                                                                                                                OTOH, philosophical progress must keep up with technological progress or mankind can build the tools to destroy itself without developing the wisdom to avoid doing so.  We seem to have dodged the bullet (for now) regarding nuclear self-annihilation, but climate change could easily do the job instead.

                                                                                                                                                                                                                                • 110. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                  morgaine

                                                                                                                                                                                                                                  John Beetem wrote:

                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                  developing the wisdom

                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                  Not a chance, if you're referring to humans.  It hasn't happened over the few millennia of what we recognize as "civilization", and there's no sign of any change whatsoever now.

                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                  It's only our technological capability that progresses, not Homo sapiens itself --- natural evolution is simply not fast enough.  The only way the leading species on the planet will "develop the wisdom" is by integrating with our machinery and in due course leaving Homo Sapiens and its self-destructive grey matter behind.

                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                  That possibility is pure speculation, alas.  There is no guarantee that our mental activity can be integrated with machinery even with full control of everything down to atomic level, so the future may unfortunately be either/or, rather than a slow evolution from our unwise past into a logical future.

                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                  Morgaine.

                                                                                                                                                                                                                                  • 111. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                    There's a report today of a guy who thinks there is a correlation

                                                                                                                                                                                                                                    between hot chips and ethernet cutting out and keyboard repeats.

                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478

                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                    "Mine gets pretty hot. Heat I don't mind, but when it does get hot,

                                                                                                                                                                                                                                    the ethernet cuts out and the keyboard repeats happen more often."

                                                                                                                                                                                                                                    • 112. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                      morgaine

                                                                                                                                                                                                                                      I see that mahjongg has become an apologist now, and doesn't even realize when he's teaching Grandma to suck eggs.  Sad.  I guess the fanboi disease over there is contagious.

                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                      The Foundation has already found the reason for dropped USB events.  No further speculation is needed.

                                                                                                                                                                                                                                      • 113. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                        Tooms

                                                                                                                                                                                                                                        Thomas Johansen wrote:

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Troy Mackay wrote:

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Tooms wrote:

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Tooms

                                                                                                                                                                                                                                        The microsope is really handy (and didn't cost me a cent), you'd be surprised what you can do when you can see what it is you are doing. I haven't even done a lot of SMD work. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Hi

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        yes i am only having an magnifying lamp the glass ones with 40 leds and it is not very good so i have been missing this for an long time..

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        I ask my local hacker space if they hade an good microscope but they only got an older fix one, have not seen it.. so i have now my own microscope on the way and hope it will be here in 7 days time and then i can try do the hack you have done..

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        I can see you only have split the VDD1V8CORE but what about the other VDD1V8ETH and VDD1V8USB ?

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Tooms

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Hi

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        hmmm replying on my own posts..

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        But i am getting (i hope ) an microscope to the coming weeking and then i will try to do the hack Troy mackay and then do some more testing to see if this fix the heat of the LAN9512 and to see how low the power the RPI can run from as i like to do an project where it is running from an battery so if i can save 30-40% in power use by do this hack and replace the LDO then it will be good.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Just hope they soon will make an fixed rev. of the board so i can buy more boards with out this error.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Tooms

                                                                                                                                                                                                                                        • 114. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                          jamodio

                                                                                                                                                                                                                                          I now find it amazing and enterteining to see that the minions resist to accept that there are problems with the R-pi. "Hey there is nothing wrong with the board, you already tested 12 keyboards, why not 13 ?" and why a kid should carry the R-pi on their backpack ? Some of us minions of the RPF carry it on our underware !!

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Sigh ....

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Meanwhile I see "no list" or any other info being "shared," and it surprises me that there is not a single bit of information on the main blog site.

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          As the issues become exponential it will start to backfire, I'd stop production and selling until the issues get fixed.

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Meanwhile APC is making progress announcing Newegg.com as distributor for US and Canada.

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          -J

                                                                                                                                                                                                                                          • 115. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                            morgaine

                                                                                                                                                                                                                                            jamodio wrote:

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            Meanwhile I see "no list" or any other info being "shared," and it surprises me that there is not a single bit of information on the main blog site.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            That's what the guy Sulge who got banned at the start of the "USB discussions getting a bit heated" thread said.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            He got banned for only a week (perhaps a sign that some admins are starting to realized that the emperor has no clothes), so let's see what he says when he comes back and points out that the very problems he was describing were confirmed by the Foundation's engineers.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            Meanwhile APC is making progress announcing Newegg.com as distributor for US and Canada.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            Excellent, that makes it a lot more likely that a UK distributor will appear before long.  The APC and BeagleBone are the only two cheap boards with Ethernet MAC directly on the SoC instead of attached over USB, so I'm very favourably predisposed to it.

                                                                                                                                                                                                                                            • 116. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                              certainly there have been plenty of opportunities on the

                                                                                                                                                                                                                                              RPi forum and twitter for someone to say yes we have a

                                                                                                                                                                                                                                              design error and it is causing chip temperatures to get hotter

                                                                                                                                                                                                                                              than they are supposed to.

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              On the recent "case with fan" thread:

                                                                                                                                                                                                                                              http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=14323

                                                                                                                                                                                                                                              bredman replies:

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              "1. The chips in the RPi are supposed to run hot, they are designed to operate safely to 120 degrees C."

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              On twitter, a similar question about fans is asked:

                                                                                                                                                                                                                                              https://twitter.com/scottfrye/status/234232917583343616

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              Liz's reponse is:

                                                                                                                                                                                                                                              "we're making good progress on the heat issue that some of

                                                                                                                                                                                                                                              you are experiencing, with expert help from the other forum."

                                                                                                                                                                                                                                              Oh wait, that's not quite what she said.  Instead she said:

                                                                                                                                                                                                                                              "Why do you need a fan?"

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              Ron K Jeffries further clarifies: "It runs very cool, even when

                                                                                                                                                                                                                                              overclocked to 900MHz.  Unless you live in the Mojave desert,

                                                                                                                                                                                                                                              you'll not need a fan."

                                                                                                                                                                                                                                              • 117. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                morgaine

                                                                                                                                                                                                                                                I think you said it best some months ago, that facts and honesty "interfere with her right to a new kitchen".

                                                                                                                                                                                                                                                • 118. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                  John Beetem

                                                                                                                                                                                                                                                  coder27 wrote:

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  There's a report today of a guy who thinks there is a correlation

                                                                                                                                                                                                                                                  between hot chips and ethernet cutting out and keyboard repeats.

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  "Mine gets pretty hot. Heat I don't mind, but when it does get hot,

                                                                                                                                                                                                                                                  the ethernet cuts out and the keyboard repeats happen more often."

                                                                                                                                                                                                                                                  Here's my latest hypothesis.  We're seeing three outcomes of the regulatory battle between RG1 (1.8V regulator) and IC3 (LAN9512).

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  1.  RG1 has substantially higher Vreg than IC3 and thus provides essentially all the current for 1V8.  IC3's regulator switches off and IC3 runs nice and cool.

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  2.  IC3 has substantially higher Vreg than RG1 and thus provides essentially all the current for 1V8.  IC3 get very hot, but still functions OK, at least for now.

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  3.  RG1 and IC3 have almost identical Vreg and the regulation is unstable, with the current alternately being sourced by RG1, IC3, or both, depending on RG1 and IC3 temperatures.

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  (3) is probably quite uncommon since it requires almost idential Vregs, but if it does occur might add enough ripple to 1V8 to cause USB and Ethernet failures.  It would be interesting to put a 'scope on 1V8 near IC3 to see what it looks like on boards with USB/Ethernet problems not otherwise explained.  It shouldn't affect IC3's PLL since the PLL has its own regulator and its own 1.8V filtering, but if IC3 is rapidly warming and cooling you might get some PLL instability.

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  It's also possible that (2) is causing local heating inside IC3 that's slowing a critical path enough to cause USB/Enet failure.  If path delay is right at the edge, process variation or case design could make the difference.

                                                                                                                                                                                                                                                  • 119. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                    morgaine

                                                                                                                                                                                                                                                    Good summary.  It's worth pointing out also that voltage is only one electrical parameter here.  If any instability is present, the added inductance from the incorrect connection could also be relevant given that the LAN9512 expects nothing but decoupling caps on these tracks.

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    The 1V8 LDO powers PLL circuitry in the LAN9512, so stability is important.  Those 3 caps won't be decoupling the LAN9512 as effectively if they're simultaneously part of a larger on-board 1.8V mesh, even if that mesh is not misbehaving electronically.

                                                                                                                                                                                                                                                    • 120. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                      John Beetem

                                                                                                                                                                                                                                                      Morgaine Dinova wrote:

                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                      Good summary.  It's worth pointing out also that voltage is only one electrical parameter here.  If any instability is present, the added inductance from the incorrect connection could also be relevant given that the LAN9512 expects nothing but decoupling caps on these tracks.  The 1V8 LDO powers PLL circuitry in the LAN9512, so stability is important.

                                                                                                                                                                                                                                                      According to the LAN9512 data sheet (Figure 2.2 -- Power Connections), the PLL has its own +3.3V to +1.8V regulator.  It appears to be wired up correctly in the RasPi schematics.

                                                                                                                                                                                                                                                      • 121. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                        morgaine

                                                                                                                                                                                                                                                        I wasn't so sure about their complete independence inside the LAN9512 when looking at the datasheet.

                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                        The VDD18ETHPLL and VDD18USBPLL lines are also connected to L3 which is specc'd at 100MHz so it seems strongly related to dynamic PLL operation (L3 is isolating ETH and USB sections from each other for RF, similar to L4 on the 3V3 side), and neither of those PLL lines has a tank cap like the 4.7uF on the 1V8CORE lines, so it doesn't seem to be caring about low-frequency stability.  That suggested to me that the PLL's 1.8V may actually be affected by the core 1V8 LDO, if not directly as a source (which seems unlikely since it's fed from 3V3) then at least indirectly through core logic.

                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                        When SMSC go to all the trouble of inductively isolating the USB and ETH sections of both their 3V3 and 1V8 LDOs, it's easy to imagine that they're not too impressed when their 1V8CORE pins are coupled to something foreign.

                                                                                                                                                                                                                                                        • 122. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                          jamodio

                                                                                                                                                                                                                                                          There are also some additional bits of information to consider based on reports of problems with Ethernet and the X1 crystal. If there are indeed power issues on the SMSC core that may produce unstable operation of the internal clock signals and ethernet is particularly picky about clock jitter and shape which may get the part to operate out of the IEEE specs. I've seen this problem with some Ethernet controllers/PHYs where temperature produces too much drift on the crystal/oscillator and the ethernet link is lost.

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          And who said that the parts on the R-pi are rated to operate at 120C ?

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          The PoP RAM chip on top of the SoC is rated for Commercial temp ranges, it varies from mobile to normal applications but it does not exceed 95C.

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          There is a lot of clueless folks at the R-Pi forum contributing wrong information to the already existing confusion.

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          -J

                                                                                                                                                                                                                                                          • 123. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                            There's a dedicated thread now in the other forum.

                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                            http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489

                                                                                                                                                                                                                                                            • 124. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                              jamodio

                                                                                                                                                                                                                                                              Love the classical cryptyc response from RPF minions ...

                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                              -J

                                                                                                                                                                                                                                                              • 125. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                morgaine

                                                                                                                                                                                                                                                                coder27 wrote:

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                There's a dedicated thread now in the other forum.

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                From that thread:

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                JamesH wrote, on the RPF forum:

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                Cannot say much about this, except that the Foundation are aware

                                                                                                                                                                                                                                                                of the problem and are working to rectify it.

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                And why exactly can the Foundation not say much about it?

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                This is a board intended for technical education, not a secret product hiding trade secrets for commercial advantage.  Why are essential items of information like the gerbers hidden?  Why are problems hidden?  Why are solutions hidden?  Why are future plans hidden?

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                I think I can summarize the questions more succinctly, if less politely:

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                Why is the Foundation full of it?

                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                Morgaine.

                                                                                                                                                                                                                                                                • 126. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                  There is a lot of clueless folks at the R-Pi forum contributing wrong information to the already existing confusion.

                                                                                                                                                                                                                                                                  +1

                                                                                                                                                                                                                                                                  Fairly clear that a lot of them are consumer level and are just blundering around in the dark..  If you dare to comment on them being clueless you just get shot down. Not worth the effort anymore IMHO.

                                                                                                                                                                                                                                                                  • 127. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                    morgaine

                                                                                                                                                                                                                                                                    selsinork wrote:

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    Fairly clear that a lot of them are consumer level and are just blundering around in the dark..  If you dare to comment on them being clueless you just get shot down. Not worth the effort anymore IMHO.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    That's a comment that applies far more widely than just to RPF's non-technical followers.  Unfortunately humanity is largely broken, the far greater proportion of it not being able nor willing to be rational.  Spok would weep in sympathy.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    It's instinctive for engineers to want to fix things, so when we see broken people, we occasionally try to convince them of their errors through clear factual and logical argument, but more often than not that's a doomed exercise since they "lack the hooks" for it to work.  More likely to succeed is appealing to emotion or self-interest, but those are not engineering methods and do not taste good to the engineering palate.  Also, most of us are not good at them.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    I think it boils down to "Choose your fights wisely".  We can't fix the clueless millions, but we can focus on RPF as a public entity which is legally accountable for what it does, and we can focus on product which does have to conform to standards when claimed and does have to operate as advertised.  Those things do provide us with hooks so we're not totally powerless to fix what is wrong.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    But no, we can't fix the clueless followers.  At best, only their descendents might be fixable through education.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    Morgaine.

                                                                                                                                                                                                                                                                    • 128. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                      John Beetem

                                                                                                                                                                                                                                                                      I just did some digging in the NCP1117 data sheet (ONsemi version).

                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                      RG1 is an NCP1117-1v8 fixed linear LDO regulator.  We have suggested that if RG1's regulation voltage Vreg is greater than IC3's (LAN9512) internal Vreg, then RG1 will supply 1.8V current instead of IC3, reducing IC3's power consumption.

                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                      The NCP1117 has a "adjustable output" version which sets Vreg using external resistors instead of internal resistors like the NCP1117-1v8.  In addition, you can adjust Vreg of the "fixed" version with an external resistor plus a stabilization capacitor.  Take a look at Figures 31 and 32.  In Figure 31, a 50 Ohm resistor between the NCP1117's GND pin and circuit GND shifts its output by 300 mV.  Figure 32 uses a variable resistor.  Shifting RG1's Vreg up by 90 mV (+5%) might do a nice job of cooling down IC3 -- probably a 15 Ohm resistor.

                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                      Figure 31 also confirms that if two NCP1117's are connected in parallel, the LDO with higher Vreg does switch off the LDO with lower Vreg.

                                                                                                                                                                                                                                                                      • 129. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                        DonQuixote

                                                                                                                                                                                                                                                                        I usually read these posts with interest to keep abreast of discoveries of potential issues with the R-Pi but these last few posts have bugged me because they are as disappointing to read as the gushing exultations of fanbois.

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        The problem with contradicting peoples' beliefs and emotions (which is one outcome of hype) is that, in general, "rationality" of the Spock-kind comes over as being pompous self-righteousness, no matter how correct someone may be (with some egos confusing "usually correct" with "infallibly correct").

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        Convincing people relies on an aspect of humanity which most technical types I've dealt with seem to lack and that aspect is empathy

                                                                                                                                                                                                                                                                        This means having to sit with the non-tehnical person in their viewpoint of the situation (because there was a time when you weren't an expert either), then guide them on a short-ish journey of self-discovery.

                                                                                                                                                                                                                                                                        In my own job (Industrial Instrument Maker/Repairer) if you had no such empathy, you would continue to be called to jobs which the 'technically unaware' had 'fixed' themselves... like the truckie who would get a $10k tanker-decanting control system to work by bashing it with a rock, but I digress...

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        In addition, regardless of how well you make an argument technically, if the points you raise do not affect the majority of people in the pursuit of whatever endeavours they choose with the device, then you'll only be arguing for the sake of hearing your own voice and having nothing better to do.

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        Let's say that as a result of this endeavour to bring down the ruthless RPF Oppressor that there is some degree of success and the RPF folds as a result of it?

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        Would you be satisfied knowing that you've been proven technically correct whilst successfully preventing the device from reaching those people whom the device may work within their requirements or that the device now costs $70.00 before adding the power supply, etc?

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        How can you hope to educate the technically-unwashed when your war has made a casualty of the only potential path they have to understanding in the near future and you've offered no tangible and immediately available alternative for equivalent cost?

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        I'd like to see less posts of the "For the glorious struggle against the oppressors of freedom that are the RPF" type and more of the "These are my findings and in day-to-day operations of type x under conditions y, then the device may fail", the likelihood of this happening (MTBF) and also  what the wider effect this has, bearing in mind that the investigations presented thus far cannot be demonstrated as being representative of a large sample of all devices produced.

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        If you want rational, be wary that you don't become irrational in your efforts to secure it.

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        Also remember that there's a difference between fit-for-purpose and a technically-perfect design, and that these states are mutually exclusive in the minds of most techie types, if the former exists at all.

                                                                                                                                                                                                                                                                        • 130. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                          Roger Wolff

                                                                                                                                                                                                                                                                          Please provide an URL to the datasheet you found. I searched for NCP1117 and

                                                                                                                                                                                                                                                                          found: http://unihedron.com/projects/sqm-le/PDFspecs/NCP1117-D.PDF as the first hit. That one doesn't have figures 31 and 32. (but you're referring to figures 28 and 29 in that datasheet).

                                                                                                                                                                                                                                                                          • 131. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                            jamodio

                                                                                                                                                                                                                                                                            Just a quick FYI, the NCP1117 you have on your board is most probably not from ON Semi but from a cheap chinese knock off.

                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                            -J

                                                                                                                                                                                                                                                                            • 132. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                              jamodio

                                                                                                                                                                                                                                                                              Would you be satisfied knowing that you've been proven technically correct whilst successfully preventing the device from reaching those people whom the device may work within their requirements or that the device now costs $70.00 before adding the power supply, etc?

                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                              There is no war and these are not issues related to "people's requirements," there are design errors and basic stuff that does not work as expected, and unless the requirements include blowing up TV's, collecting power supplies, USB hubs, keyboard, mouses and SD cards, like it or not the R-Pi has design and functional problems that need to be corrected so the people that are the main target for this device can receive what they expect.

                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                              About the cost, RPF continues to provide a bogus and misleading statement on their home page ...

                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                              -J

                                                                                                                                                                                                                                                                              • 133. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                John Beetem

                                                                                                                                                                                                                                                                                Roger Wolff wrote:

                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                Please provide an URL to the datasheet you found. I searched for NCP1117 and

                                                                                                                                                                                                                                                                                found: http://unihedron.com/projects/sqm-le/PDFspecs/NCP1117-D.PDF as the first hit. That one doesn't have figures 31 and 32. (but you're referring to figures 28 and 29 in that datasheet).

                                                                                                                                                                                                                                                                                http://www.onsemi.com/pub/Collateral/NCP1117-D.PDF

                                                                                                                                                                                                                                                                                • 134. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                  John Beetem

                                                                                                                                                                                                                                                                                  jamodio wrote:

                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                  Just a quick FYI, the NCP1117 you have on your board is most probably not from ON Semi but from a cheap chinese knock off.

                                                                                                                                                                                                                                                                                  Quite true, so we can pretty much expect that it won't regulate as precisely as a real ON Semi part -- where "real" has to be taken with a grain of element14 dioxide in these days of counterfeit chips.  OTOH, they probably did faithfully copy the NCP1117 circuit (and probably reverse-engineered the masks too) so I expect some  resistor value to work :-)

                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                  Now if anyone tries the resistor trick, be sure that 1V8 doesn't get too high -- I wouldn't go above 1.9V as this would cause excess power consumption inside IC3 and the SDRAM.  Power consumption increases linearly with frequency and quadratically with voltage, so you don't want the extra switching power consumption of IC3's 1.8V logic to exceed what was saved by switching off IC3's internal LDO.

                                                                                                                                                                                                                                                                                  • 135. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                    morgaine

                                                                                                                                                                                                                                                                                    Steve Lockett wrote:

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    Convincing people relies on an aspect of humanity which most technical types I've dealt with seem to lack and that aspect is empathy

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    Empathy is helpful in education because it assists the educator to understand why understanding is not being communicated, and in many cases this allows a different tack to be taken which can be successful.

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    But empathy by the educator cannot override deliberate denial of facts and dismissal of rational arguments by the person they are trying to educate.  Nor can it overcome malicious responses like shutting down rational discussion, and that is what we are seeing in the RPF forums.  Perhaps it's not too surprising that denial has become so common among RPF forum posters, since they're following the appalling example set by RPF leaders.

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    As I tried to explain earlier on, our topic here has nothing to do with "technical vs non-technical", nor "informed vs uninformed", which is how you tried to portray it.  It is targetted purely at those who willfully reject information and deny the whole process of critical inquiry because it conflicts with irrationally held beliefs or some agenda.

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    Not knowing is the normal state of affairs, and we are all deeply immersed in it.  Not wanting to know and actively preventing others from learning through open discussion is a completely different condition, and it's deeply pathological for a thinking species.  I have no empathy with it whatsoever, because it is harmful to the educational goals of this project and a direct attack on the engineering process and the scientific method which are key to future generations of engineers.

                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                    Morgaine.

                                                                                                                                                                                                                                                                                    • 136. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                      Figure 31 also confirms that if two NCP1117's are connected in parallel, the LDO with higher Vreg does switch off the LDO with lower Vreg.

                                                                                                                                                                                                                                                                                      The engineer in me asks which electrical characteristic on the datasheet defines the voltage differential required to turn the regulator off? 

                                                                                                                                                                                                                                                                                      • 137. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                        tmackay

                                                                                                                                                                                                                                                                                        I spotted that too but initially dismissed the idea since I thought they must be assuming constant current drain for those figures based on my misunderstanding of how these regulators worked.

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        From the description of the adjustable variety, and assuming the fixed version is basically the same with internal resistance, the GND pin is a constant current source (with unknown current due to unknown internal resistors) with a negligible contribution from the internal reference "pin".

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        "For the fixed output devices R1 and R2 are included within the device and the ground current Ignd, ranges from 3.0 mA to 5.0 mA depending upon the output voltage." - from the datasheet in question.

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        I can't see anywhere on the datasheet what these internal resistances are or if it is even consistent since the output voltage depends largely on the ratio of these two resistors.

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        From the two examples for the fixed XT50 we can work out the internal resistance, but I don't get consistent results:

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        5V=1.25V(1+R2/R1) -> R2/R1 constant

                                                                                                                                                                                                                                                                                        5.3V=1.25V(1+(R2+50Ohm)/R1) -> R1=50Ohm x 1.25/0.3=208Ohm

                                                                                                                                                                                                                                                                                        12V=1.25V(1+(R2+2kOhm)/R1) -> R1=2kOhm x 1.25/7=357Ohm - perhaps that's approximately 12V?

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        At at any rate, I don't think this is well described by the datasheet. The fact that they included that use case seems to suggest it is supported but don't give the required information to work out the details. I guess it's one of those try it and see kind of designs. I've also got some adjustable regulators here I was planning to try but haven't had time.

                                                                                                                                                                                                                                                                                        • 138. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                          7point62

                                                                                                                                                                                                                                                                                          Hi all, first post from another refugee...

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          selsinork wrote:

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          Figure 31 also confirms that if two NCP1117's are connected in parallel, the LDO with higher Vreg does switch off the LDO with lower Vreg.

                                                                                                                                                                                                                                                                                          The engineer in me asks which electrical characteristic on the datasheet defines the voltage differential required to turn the regulator off? 

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          It's simply the way that the average linear regulator works (caveat alert: there's no schematic in my 1117 datasheet, so I'm assuming a standardish circuit). A linear reg (very basically) dumps current into a load while monitoring the voltage on it's output pin with reference to it's ground pin. A feedback loop varies the current from input to output to keep the output pin at setpoint. If you apply a voltage higher than setpoint to the output pin via a low impedance source the regulator has no way of dumping current from output to to ground internally, so the output voltage is pulled high. The internal error correction then takes a dump (technical term!). So then in this case, the regulator with even a marginally higher output voltage supplies all the current to the surrounding circuitry, while the other is shut down. As has already been mentioned there may be parasitic oscillation, thermal effects... allsorts going on too. There's no easy way to make fixed regulators work in parallel either - best to let the right one do all the work! What's the upper voltage limit of the 1V8 line anyway?

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          Hope this all makes sense.

                                                                                                                                                                                                                                                                                          • 139. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                            There's a report today that adding a heatsink cures networking problems:

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478&start=4

                                                                                                                                                                                                                                                                                            by lajos » Thu Aug 16, 2012 3:01 pm

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            So I did an experiment. I installed heatsinks on both the SOC and memory chip. It's a small heatsink, the SOC still gets pretty hot (I don't have a surface thermometer, but it's not comfy to the touch.) But now the ethernet works without dropping out.

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            Before heatsink, I would get at tops 40-50KB/s transfer rate, with frequent stalling, with heatsink I can move large files at ~2.0MB/s.

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            Although there is a contrary report as well:

                                                                                                                                                                                                                                                                                            http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=12097&start=247

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            I added a radiator to the chip but there was no difference. Perhaps it was too small.

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            • 140. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                              jamodio

                                                                                                                                                                                                                                                                                              That is sort of a synonym for "unreliable."

                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                              -J

                                                                                                                                                                                                                                                                                              • 141. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                jamodio

                                                                                                                                                                                                                                                                                                Time keeps going by and I don't see any information being shared by Pete or anybody from RPF about the issues and what we can expect to get them fixed.

                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                -J

                                                                                                                                                                                                                                                                                                • 142. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                  Jamodio,

                                                                                                                                                                                                                                                                                                    right, Pete has gone silent, and JamesH says he can't say much.

                                                                                                                                                                                                                                                                                                  Pete said he was in full-duplex communication with SMSC, but

                                                                                                                                                                                                                                                                                                  apparently he's not eager to share.

                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                  People have asked for gerbers to see if there's a way to disconnect

                                                                                                                                                                                                                                                                                                  1.8v by drilling a hole in a strategic place, but no response.

                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                  That doesn't mean progress isn't being made, such as people

                                                                                                                                                                                                                                                                                                  experimenting with heatsinks.   Maybe SMSC could be asked

                                                                                                                                                                                                                                                                                                  if the networking problems are a plausible result.  Maybe someone

                                                                                                                                                                                                                                                                                                  will use sandpaper to reveal exactly how the power is connected.

                                                                                                                                                                                                                                                                                                  • 143. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                    morgaine

                                                                                                                                                                                                                                                                                                    coder27 wrote:

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    People have asked for gerbers to see if there's a way to disconnect

                                                                                                                                                                                                                                                                                                    1.8v by drilling a hole in a strategic place, but no response.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    I've seen people ask for gerbers just for openness on principle, but not for that specific diagnostic purpose.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    If that request was made in a place which RPF could not have missed, and they responded with silence, it's worse than I thought.  They don't even value help from their dedicated supporters.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    The Foundation is rapidly losing all the little credibility that's left.  What a bunch of self-centered and myopic incompetents.

                                                                                                                                                                                                                                                                                                    • 144. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                      Morgaine,

                                                                                                                                                                                                                                                                                                        see the first two posts in this thread regarding where to drill.

                                                                                                                                                                                                                                                                                                      http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489

                                                                                                                                                                                                                                                                                                      • 145. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                        Roger Wolff

                                                                                                                                                                                                                                                                                                        Guys, everybody is blaming the 1.8V problem for the keyboard repeat problems. However, the source of the keyboard repeats has been found, and it is that USB interrupts are delayed more than 1ms. The cause for this is the SD card driver. That is why morgaine is now using an USB stick for his root.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        The kernel/sd card driver will be fixed in time. In parallel other people can fix the 1.8V problem, but I haven't seen a confirmed problem caused by this.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        The 0.15W extra power in the LAN chip will raise the temperature of the LAN chip by a few degrees. Maybe 10. This should be within range of what is allowable.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Diagnosing "intermittent" problems is difficult. people see patterns way too quickly. You have to try with and without a few times and reproduce the problem consistently with one setup and not with the other.

                                                                                                                                                                                                                                                                                                        • 146. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                          Roger,

                                                                                                                                                                                                                                                                                                            I don't think the keyboard repeats problem is quite so well understood.

                                                                                                                                                                                                                                                                                                          User Max still reports problems with the Enter key.

                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                          http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=12097&start=241

                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                          If SMSC is telling Pete not to worry about the LAN chip, then he would

                                                                                                                                                                                                                                                                                                          probably be eager to share that. 

                                                                                                                                                                                                                                                                                                          • 147. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                            Roger Wolff

                                                                                                                                                                                                                                                                                                            Coder, SMSC is NOT telling pete not to worry. Someone else asked SMSC and got told: "No way!".

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            In some "circles", the understanding is that oscilations will result if you parallel two linear regulators. This is not always true. In many linear regulator datasheets they recommend the parallel setup for situations where you need up to 2x the current of just one of the regulators.

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            With Pete's preoccupation with "sufficient decoupling", this means that I really don't expect any oscilations.

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            SMSC says the regulator should not provide external current. Fine. But what happens if you do draw current? You might cause the SMSC regulator to drop into the "dropout" region. So it will be in "constant current" mode. So regulation is delgated to the RG1 regulator. Still the voltage will remain within tolerance.

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            This means that the only problem is that 0.15W is dissipated in the SMSC chip, instead of the RG1. As said before.

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            With "intermittend problems", and interrupt problems not completely fixed, I'm not too worried about the single report that mentions an enter-keyup event going missing.

                                                                                                                                                                                                                                                                                                            • 148. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                              jamodio

                                                                                                                                                                                                                                                                                                              I don't agree that everybody is blaming the 1.8V problem to keyboard repeats or anything else related to USB, at least I don't.

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              That's is simply a clear and flat error that needs to be fixed, again we can theorize and overanalyze the potential side effects of the error but it does not fix it and there are so many variables and other issues that make things not work for some folks and work for others.

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              I don't believe much that the USB problems are related to this one, I'd lean more in the direction that we are trying to squeeze a full featured USB host from a flaky USB OTG not very well known and coded on the drivers implementation.

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              -J

                                                                                                                                                                                                                                                                                                              • 149. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                jamodio

                                                                                                                                                                                                                                                                                                                It is not clear who is telling who what, but what is pretty clear is that we are not being told anything !!

                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                I strongly believe that at this instance the distributors should stop producing and selling the current revision of the board, which is clearly faulty.

                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                -J

                                                                                                                                                                                                                                                                                                                • 150. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                  Roger Wolff

                                                                                                                                                                                                                                                                                                                  Flaky? I have the impression that the hardware is not flaky. Its just that the hardware is a bit minimal. It defers to software all that CAN be deferred to software. Together with the minimal documentation, and interactions with other Linux drivers, it turns out that it's not quite finished yet.

                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                  ... stop selling ... faulty.....

                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                  They clearly should continue selling the boards, which "work for  me".

                                                                                                                                                                                                                                                                                                                  With a $1 heatsink on the lan chip you can (over) compensate for the extra heat if you want.

                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                  Part of "getting this software problem fixed" is in getting enough devices out in the field so that some brilliant linux-hacker gets one and says: Oh, this is a simple problem to fix, and fixes the driver-problem. The original plan was to get 10k units out to just Linux-hackers. But how do you restrict access to the people you want? Impossible. The only way is to flood the market, and hope the right people obtain one.

                                                                                                                                                                                                                                                                                                                  • 151. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                    jamodio

                                                                                                                                                                                                                                                                                                                    From a power supply design is both flaky and faulty, from a user perspective is flaky and unreliable.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    I've a heathsink on both the SoC and SMSC and that does not fix the problems with USB.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    When I found and detected the 1V8 problem I didn't have a R-Pi board in my hands, the error was just clearly visible in the schematics.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    We already know that the "original plan" was badly exectued by the RPF folks, they didn't listen before, during and after the launch, and they continue on that behavior.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    Flooding the market with a faulty product is not a reasonable and measurable approach to fix problems and improve hardware/firmware, putting the boards on the right hands would have been more effective, hope is not a very reliable tool of engineering.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    I said it many times already, I'm not a fanboi but neither a detractor of the R-Pi, I still consider it a good idea, something worth to have, but it needs to get FIXED !!

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    -J

                                                                                                                                                                                                                                                                                                                    • 152. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                      jamodio

                                                                                                                                                                                                                                                                                                                      Let me add another one ...

                                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                                      Performance seems to be an issue for some folks, so what you can do ? "over clock it,", but that will void your warranty and it is somehting

                                                                                                                                                                                                                                                                                                                      we (RPF) can't recommend officialy ...

                                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                                      That's flaky++

                                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                                      -J

                                                                                                                                                                                                                                                                                                                      • 153. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                        Roger Wolff

                                                                                                                                                                                                                                                                                                                        If performance is an issue for you: BUY SOMETHING ELSE!

                                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                                        When you overclock, chips get hotter than what they (and/or their cooling system) were designed for. If you overclock your desktop, and burn the CPU, that's your own fault. Due to errors in the system, you might not get caught if you bring it back to the shop and claim it was a manufacturing error and want it exchanged.

                                                                                                                                                                                                                                                                                                                        • 154. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                                          Hope this all makes sense.

                                                                                                                                                                                                                                                                                                                          Possibly, but everything you say is based on assumption with no actual reference to defined behaviour.

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          There was a very simple reason for asking that question. If the behaviour is not defined you have no basis to rely on it, you simply don't know if it'll work or not. Saying "It's simply the way that the average linear regulator works" is not an acceptable substitute for actual defined behaviour.  Doesn't anyone question why the behaviour isn't defined ?

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          The only reference appears to be Figure 31 and that suggests you need 300mV to (reliably?) turn the regulator off. So how does the SoC, RAM etc react 2.1v on it's 1.8v input ?

                                                                                                                                                                                                                                                                                                                          On the other hand, if it's only a couple of mV then you'll have lots of fun with oscillations as the voltage measurably changes by a few mV depending on how you load the cpu/gpu.

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          Without a definition of the behaviour it's only ever going to be a bad engineering decision to use it, rely on it, or expect it to work.

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          Also we don't know what the 1.8v regulator inside the lan9512 is or what it's defined behaviour is, it could be a 1117 clone, or could be something vastly different in design, we simply don't know. We do have an answer from SMSC saying it's not designed to be used this way.

                                                                                                                                                                                                                                                                                                                          • 155. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                            morgaine

                                                                                                                                                                                                                                                                                                                            Roger Wolff wrote:

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            They clearly should continue selling the boards, which "work for  me".

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Let's pin that one up on the Logical Fallacy of the Day board and move onto something more interesting,.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Part of "getting this software problem fixed" is in getting enough devices out in the field so that some brilliant linux-hacker gets one and says: Oh, this is a simple problem to fix, and fixes the driver-problem. The original plan was to get 10k units out to just Linux-hackers. But how do you restrict access to the people you want? Impossible. The only way is to flood the market, and hope the right people obtain one.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            That paragraph makes no sense, because at the time that the 10K were envisaged, the Foundation didn't know about these faults so they couldn't possibly have even envisaged that there was anything to fix.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Be that as it may, it became even less plausible when RPF decided to advertise the device as a capable media player and to market it to all and sundry rather than only to developers.  That transformed your already questionable premise of "sell in the hope of a fix" into a completely unreasonable one.  You don't sell a product to hundreds of thousands of users in the hope that a problem which you don't realize exists will be fixed.  It may have the merit of being funny, but we're not aiming for comedy here..

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            The Pi is a board with 3 USB-related faults which have just recently been accepted by the Foundation:

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            • 1.8V board design fault which is acknowledged to be out of spec, and which we know from basic principles can result in excess power dissipation in the LAN9512 in an unknown proportion of boards.
                                                                                                                                                                                                                                                                                                                            • Extreme USB endpoint constraints which prevent Pi from being used like a normal USB host that works with a reasonable number of devices attached to hubs.  These constraints are like none ever experienced by ordinary computer users on any kind of host computer equipment whatsoever, and must be bewildering.  From any reasonable user perspective, this constitutes a major equipment fault.
                                                                                                                                                                                                                                                                                                                            • USB operation is acknowledged to lose data intermittently, because the driver requires realtime response from the Linux kernel when handling USB's split transactions. Since Linux is not a realtime O/S, those transactions can fail depending on random Linux scheduling, and so the Pi's USB system is plagued with intermittent USB data loss.  This is extremely serious, and is unprecedented in any well known Linux system.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            A normal product on the market would almost certainly be withdrawn from sale if such a catalogue of faults came to light.  Also quite likely, the units it has already sold would be placed under voluntary recall, not for safety but out of sheer embarrassment.  Problems on this scale could destroy a well-known brand like Apple i* or Google Nexus.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            The Pi is not a normal product of course, and the Foundation is not known for acting rationally which complicates the matter still further.  On top of this, one should add that their Apple-like Reality Distortion Field has made some unknown but vocal proportion of Pi owners consider faulty boards to be satisfactory, and also that the $35+shipping cost of Pi is low enough that more than a few owners don't really care that the board has a few problems.  Far outweighing these considerations though, the Pi is not a normal product because RPF are driven by image making and facial egg, not by a desire for good engineering and open honesty..

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            One can only guess what course this will take, but from past precedent my guess is that they will put their spin machine into high gear and declare that no important problems existed and that nobody significant was affected, while secretly trying to remedy these severe issues which affect vast numbers of people.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            For our part, I expect we'll just have to live with this dysfunctional little board and work within its limitations until a better version appears.  We can then deposit this original on the mantlepiece as an engineering curiosity.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Morgaine.

                                                                                                                                                                                                                                                                                                                            • 156. Re: RG1 1.8v regulator
                                                                                                                                                                                                                                                                                                                              DonQuixote

                                                                                                                                                                                                                                                                                                                              Hi Morgaine,

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              The last OT from me in this thread, I promise!

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              I didn't understand what the point was with the criticisms directed towards the Foundation.

                                                                                                                                                                                                                                                                                                                              For whatever reason, I did read the comments I referred to as being technical vs non-technical and so took that stance to pose the question and comments.

                                                                                                                                                                                                                                                                                                                              Given your response above, I wholeheartedly agree with you on the points of education and for whatever it's worth, I understand the frustration.

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              If you felt that I was trying to portray you as something which you obviously aren't then I apologise for my clumsy probing for an explanation. I should know better than to post after 10:00pm!

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              Cheers

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              Steve

                                                                                                                                                                                                                                                                                                                              • 157. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                                                Part of "getting this software problem fixed" is in getting enough devices out in the field so that some brilliant linux-hacker gets one and says: Oh, this is a simple problem to fix, and fixes the driver-problem. The original plan was to get 10k units out to just Linux-hackers. But how do you restrict access to the people you want? Impossible. The only way is to flood the market, and hope the right people obtain one.

                                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                                Roger,

                                                                                                                                                                                                                                                                                                                                  Of course there is a way to restrict access to the people you want.  You declare the item

                                                                                                                                                                                                                                                                                                                                to be in beta test.  On the front page you talk about what issues are known, and what is

                                                                                                                                                                                                                                                                                                                                being done to resolve them.  Of course, that doesn't prevent over-eager buyers from

                                                                                                                                                                                                                                                                                                                                buying the product and then complaining when they are disappointed, but it gives you

                                                                                                                                                                                                                                                                                                                                a good answer that you made a good faith attempt to disclose.

                                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                                   Instead, the front page highlights only the happy stories, showing pictures of

                                                                                                                                                                                                                                                                                                                                7-year olds, with no indication whatsoever that the product is not intended for

                                                                                                                                                                                                                                                                                                                                general use.  In fact, when asked if the product is in beta test, a firm "no" is the

                                                                                                                                                                                                                                                                                                                                response.  Bug fixing is happening, but it is happening in off-site github repositories,

                                                                                                                                                                                                                                                                                                                                and is "pushed" to end users through low-visibility mechanisms.

                                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                                Hardware errors are in a different class than software errors, since it is possible

                                                                                                                                                                                                                                                                                                                                to fix software errors in the field by means of downloading new versions. 

                                                                                                                                                                                                                                                                                                                                Intentionally selling known faulty hardware that apparently can't be fixed in

                                                                                                                                                                                                                                                                                                                                the field doesn't strike me as something a responsible organization would do.

                                                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                                                I suspect that Maplins signed on as a retailer without knowing of the 1.8v problem.

                                                                                                                                                                                                                                                                                                                                When they find out, it will be interesting to see what they do.  I also wonder if

                                                                                                                                                                                                                                                                                                                                they know about the claimed PCB problem that prevents residential FCC/CE

                                                                                                                                                                                                                                                                                                                                certification.  The foundation may not be worried about its reputation, but

                                                                                                                                                                                                                                                                                                                                I think Maplins would be.

                                                                                                                                                                                                                                                                                                                                • 158. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                                                  jamodio wrote:

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                  I don't agree that everybody is blaming the 1.8V problem to keyboard repeats or anything else related to USB, at least I don't.

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                  That's is simply a clear and flat error that needs to be fixed, again we can theorize and overanalyze the potential side effects of the error but it does not fix it and there are so many variables and other issues that make things not work for some folks and work for others.

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                  ...

                                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                                  Jamodio,

                                                                                                                                                                                                                                                                                                                                    While this certainly is an error that needs to be fixed, I think it does help

                                                                                                                                                                                                                                                                                                                                  to theorize and analyze.  When you first pointed out the schematic error,

                                                                                                                                                                                                                                                                                                                                  that wasn't enough to get any traction.  But then when further analysis and

                                                                                                                                                                                                                                                                                                                                  experimentation showed the connection to the hot lan chip, that was

                                                                                                                                                                                                                                                                                                                                  motivation to contact SMSC.  And when they replied, that got the

                                                                                                                                                                                                                                                                                                                                  attention of element14, and they got Pete's attention.

                                                                                                                                                                                                                                                                                                                                    At this point, the problem isn't considered serious enough for Maplins

                                                                                                                                                                                                                                                                                                                                  to put a hold on the product, or for either of the distributors to make

                                                                                                                                                                                                                                                                                                                                  a formal disclosure.  If further theorizing, analysis, experimentation,

                                                                                                                                                                                                                                                                                                                                  and contact with SMSC can provide a link to USB and/or networking

                                                                                                                                                                                                                                                                                                                                  misbehavior, that would provide more incentive to promptly fix the

                                                                                                                                                                                                                                                                                                                                  problem, both for future customers and current customers.

                                                                                                                                                                                                                                                                                                                                  • 159. Re: RG1 1.8v regulator

                                                                                                                                                                                                                                                                                                                                    jamodio wrote:

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    It is not clear who is telling who what, but what is pretty clear is that we are not being told anything !!

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    I strongly believe that at this instance the distributors should stop producing and selling the current revision of the board, which is clearly faulty.

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    -J

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    Jamodio,

                                                                                                                                                                                                                                                                                                                                      You are not the first to suggest this.

                                                                                                                                                                                                                                                                                                                                    On the RPi.org forum, user lajos wrote:

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                       "I hope this next suggestion won't be taken the wrong way... but would it make sense to tell buyers that these are known hardware issues, or even stop manufacturing and sales until they are fixed?"

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    Amazingly, he hasn't been banned, belittled, or had the thread locked.

                                                                                                                                                                                                                                                                                                                                    So maybe the RPF is actually considering that.

                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478&start=10