3 Replies Latest reply on Nov 28, 2012 11:05 AM by mynameisJim

    Headless setup for Rpi 2.0 with 5V switching power supply ...


      Finally had some time to put together a small prototype board with the switching power supply and setup the Rpi with low profile microSD and root on a small USB memory drive.


      Here is how the whole thing looks like:



      And from the bottom:



      On the connector besides input power to the switching power supply I've the UART Tx and Rx signals for the serial console just used for initial setup.


      Instead of a full size SD card or a microSD with the SD adapter I used Adafruit's low profile microSD adapter:



      The root file system is mounted via USB on a 16GB memory stick from Verbatim:



      The case is obviously Adafruit's crystal-clear acrylic enclosure:



      If you didn't notice, I also added a small push button for RESET.


      The power supply is based on Texas Instruments TPS54232D.TPS54232D. SWIFT Step Down DC/DC converter:



      It can take from 7V to 28V and deliver up to 2A 5V output


      Here is a close up to the prototype board:



      And here are the schematics:


      As time permits I may design a pcb layout using SMT components that will make the board much smaller.


      So far the whole thing seems to be working OK, with the USB drive mounted, overclocked at 900MHz (500MHz for SDRAM and 275MHz for gpu) and ethernet with active traffic (I'm using the Rpi via ssh and VNC) it takes about 260mA at 9V.


      There is a substantial different in temperature from the Rev 1.0 board, the LAN9512 now runs barely warm, still with the case fully closed touching the case feels worm and a thermocouple probe it shows about 42C inserted through the flat cable opening.



        • Re: Headless setup for Rpi 2.0 with 5V switching power supply ...

          That's excellent, jamodio!  And the TPS54232D.TPS54232D. costs only 3 quid so this looks very effective on all fronts.


          The BOOT control on the TPS could be the basis of an interesting design for a cluster of Pi boards providing individual  power control activated by software on a master board, and at 1 uA shutdown drain it looks great for battery-powered low duty cycle operation too.

            • Re: Headless setup for Rpi 2.0 with 5V switching power supply ...

              Thanks Morgaine,


              I really like the TPS54232D.TPS54232D., I've used in several designs and it's very efficient and reliable, there are other alternatives but I'm really happy with this one and I like the wide input voltage range, I've it in some boards used for process control powered from a PLC 24VDC power supply. I've been testing it for over a year and no glitches.


              Not a major concern but things get "worm" inside the enclosure, I have only one from Adafruit, will try to get another one for a Rev 1.0 board and see what it shows, so far for this one:


              root@raspi2:/# /opt/vc/bin/vcgencmd measure_temp



              I'm still debating with myself if to keep the root file system separate on a USB stick or just leave it all together in a mcroSD card, memory leveling effects will happen on both anyway so not sure about if this is an optimal configuration also taking in account the USB driver issues. Any comments ?