|Product Performed to Expectations:||9|
|Specifications were sufficient to design with:||10|
|Demo Software was of good quality:||6|
|Product was easy to use:||7|
|Support materials were available:||9|
|The price to performance ratio was good:||8|
|TotalScore:||49 / 60|
Some sections still changing...
3 Jan 2019 First Publish
15 Jan 2019 Updated memory depth
How I met Piscoscope for the fist time
I first met picoscope at my university research lab, but didn't use it. Back then the faculty still use cathode ray tube type and i use it too. My first heavier usage on scope was on my final year project to develop the video digitiser. Although i have long lose the free website, it miraculously survived on another site http://www.oocities.org/collegepark/quad/4505/stereov/stereo.html . It was handy in showing the PAL TV signal and for the next couple of years, one of my interest is to use oscilloscope to look at TV signal. It is somewhat challenging to freeze the TV signal on the CRT scope, but soon as i start to have access to some Tek digital storage scope, things start to become easier. I start to have the thought of wanting to store longer record of such signal but have never found one under box oscilloscope, including the high end infinium 86000 series in my postgraduate lab. Somewhere in 2012, while working on a system integrator project, we were required to sample the signal of a BLDC motor contor circuitry up to 30s, and the same low memory depth of box oscilloscope hampers us of achieving the goal. By chance, i rediscovered picoscope (although i have being looking at its advertisement on and off on magazine) and was amazed by the big surplus of memory depth compared to box oscilloscope. I made the jump to use a Picoscope 5204 with has 128MS (mega sample) of memory depth.
As comparison, a current up to date Tektronix MSO/DPO200B has 1MS memory depth. To me, this is still the one of the biggest draw of Picoscope, its tremendous memory depth that makes it able to function like a real-time data acquisition card (in fact we also use it with DAQ functionality).
Couple with its headless (no display) form factor, it is very suitable for use at tester and save a significant amount to space and power. Let's now see whether its other oscilloscope functionality is up the the requirement.
The equipment comes in a xxx box weighing about
The contents of the boxes are shown in the next 3 photos
Figure 1 5444D main unit and digital cable
Figure 2 Probe
The next photo is an one page cheat sheet to use the 5444D
Figure 3 cheat sheet
About PicoScope 5444D MSO
The 5444D MSO is a mixed signal oscilloscope with 200MHz bandwidth. It has a maximum 1GS/s at 8bit and 62.5MS/s at 16bit. Memory wise, it is equiped with 512MS memory depth at 16 bit. It has built in AWG but not signal generator (as per listed in product page as well as the specifications table on https://www.picotech.com/products/oscilloscope-specifications .Take note, however, on the PicoScope 6 software, it won't tell if the scope one use is equipped with signal generator or not. it can be powered by USB
Mechanical & Built
The first thing i look at is the USB connector. The 5204 that i use before has a USB type B connector, similiar to connector used in device like printer. The drawback is that if it is used in a tester or machine which is subjected to vibration, the connector might eventually loosen.
This results in machine failure which is sometimes difficult to trace. For 5444D it is using USB 3.0 type B connector, which is somewhat more secure, but i am unsure if it will still loosen after long time usage on machine. A possible improvement for future model would be to provide screw lock USB connector to hold it into position
reference on USB connector : https://en.wikipedia.org/wiki/USB_(Physical)
For installation, i follow the cheat sheet and proceed to https://www.picotech.com/downloads
The softwares are available for Windows, Mac and Linux.
For Windows, there are a couple of softwares, namely
Unfortunately, there is no SDK supported for 5444D MSO. After communicating with the helpful element14 and picoscope personnel, i got the specific sdk from them. The sdk, which is also available for Raspberry Pi and Beaglebone, is providing programming interface to other software like C++, C#, MATLAB, Labview.
Because of this i am not able to test 5444D MSO with these other platforms, something which i have originally wanted to. Subsequently i have tested it with MATLAB.
using it as DAQ. Due to its huge memory depth, we can use it as a real time DAQ. This is especially useful when the the signal sampled is faster than the USB connection speed. What we do is simply store all the samples on Picoscope, and retrieve it when necessary via programming API. A more detailed elaboration of the application of high memory depth, with many of the PicoScope family has, is at Picoscope memory depth application calculation . For PicoScope MSO 5444D, which has 512MS memory depth at 16 bit
|Sampling rate||Maximum time to capture until buffer is full|
|1 GS/s at 8 bit||=2*512e6/1e9=1s|
|62.5MS/s at 16 bit||=512/62.5= 8.192s|
Take note that these are at max sampling rate. In practice we may want to sample at speed that is more suitable to our application
More detailed discussion can also be available at https://www.picotech.com/library/oscilloscopes/deep-memory-high-performance-oscilloscopes
Size matters #2
The second size here is the physical size of the USB scope. In one of my actual tester setup, i have 4 PicoScopes and they only occupy space less than a single box oscilloscope. Having said that, i find the road test unit very conveniently placed on my already crowded home work desk. As my work desk, and i believe most people work desk will have access to a monitor or laptop, a USB oscilloscope does make sense. I do actually try even further by hooking up a raspberry pi with touch screen to the scope, making it essentially a box oscilloscope.
The probe & Basic Usage
To start using the probe, the probe leaflet instruction as well as the scope user manual provide instruction. What is not clear, however, the voltage level. In the figure, this is using the probe in x10 position (following the probe leaflet). It is unsure what is the benefits of setting to x10 in this case.
I also try the x1 position, which shows the real voltage level
Figure Measurement in x10 position
Figure Measurement in X1 position
it is somewhat noisy if the probe is too near to the scope itself, as seen from the two figures below. Figure 1 is i place the probe further from the scope. Figure 2 is when i leave the probe on the casing of the scope. Take note that it is mear 3 mV but it is still interesting to take note that we don't place DUT at the noisy area
as i try to calibrate the probe as per its instruction, i find that i am measuring at 0.2V instead of 2V peak to peak. I realize that the scope can be powered by USB or by power supply. I would think if it is good to know the power supply stage of the scope, whether it is bus powered or socket powered.
The scope comes with four channels. When use with more than 1 channel, one can set the offset of the overlapping channel by clicking its respective colour in the bottom of the screen. The other functionalities of the PicoScope is similar to most box instrument but as all the functions is in some menu rather some physical button on box instrument, the best way is to familiarize oneself with the menu. The "An Introduction To PicoScope" comes in very handy here.
Figure above shows the channel C signal is offset by 9%
There is also a built in Help system with the PicoScope 6 user's guide where one can browse for function that we want
I try to refer to this built in menu and it is easy to understand and follow.
Now let's look at selected functionality of the USB scope. One stand out point of PicoScope is that all these functionalities comes at no additional or optional charge to the user. Comparing to most other box scope in the same range, getting any of such extra feature is an option. For example, MSOX3024T from Keysight cost USD$1128 for application in automotive serial triggering for signal such as CAN.
The 5444D MSO comes with 16 serial decoding. I have chosen to test with automotive signal. 5444D MSO supports CAN and CAN FD. For this, i test with an aged arduino can bus shield v1.1 generated CAN bus. One good thing with 5444D MSO is its 512MS deep memory can capture thousands of packets. Moreover, the PicoScope 6 software comes with functionality to search and filter through all these captured packet.
with just the basic autoset on oscilloscope trace (on channel A) for a CAN signal, one will see trace like figure below
With the built in serial decoding on CAN bus, i setup the scope to measure the CAN signal generated by an Arduino CAN-Shield v1.1.
PicoScope offers the display as graph as well as table.
Details of the setup is mentioned in CAN bus testing with PicoScope 5444D . There is separate blog on CAN bus testing with PicoScope 5444D
CAN bus is a differential signal, with CANL and CANH, where CANL is the inverse of CANH signal. Measuring the difference between the two removes any common-mode interference encountered by the signal during transmission.
One can use a differential probe with differential scope such as PicoScope 4444 for best measurement. However, with PicoScope 5444D MSO, single ended measurement can still be made.
With the channel A probe tip connecting to the CANH of the can-shield, and the probe ground connected to the oscilloscope ground, i get this trace.
It should be taken note that any common-mode noise will be displayed and may cause errors in decoding on the my PicoScope 5444D MSO. This, however, will not affect the CAN receiver (take note there is none in my case).
to make the measurement, we start by looking at what is offered at PicoScope 6. Picoscpe 6 provide some quick settings on the toolbar, that enables use to change the time scale, the sampling rate and the data length. Once we start changing time scale, we start to see the CAN packets coming in, as in figure below.
Since i have selected both the graph table in the serial decode setup step, i get the color corded trace in the graph display. The acquired data is time correlated. In table, the data is presented in table format. We can do a few useful measurement with table. Firstly, if we double click a frame in graph format the corresponding frame will be highlighted in table.
We can then save the trace with .psdata extension
A total of 20 probe clips of the hook-on type are supplied, 16 red ones (data) and 4 black (ground). These connect to a 20-way cable terminated with a polarized IDC connector to link to the 2208B MSO instrument. Wires in the cable are numbered D0-D15 and GND (4x) for correlation to the 16 traces that appear in the signal window.
one suggestion is possibly to label it at both side of the pin, as it can be difficult to navigate
I do a very simple test with this, i connect one of the probe to the AWG output on the back of the chasis. The 5444D MSO doesn't come with signal generator however the PicoScope 6 software won't give a hint on that. the option to run signal generator is still there but it won't function.
One access the AWG via a few clicks
first click on Arbitrary, edit the waveform to what we want, exit, and tick Signal On
i then connect the probe to another probe on channel A and hit auto setup and voila i gets the signal
I then follow on with other editing function of the AWG
and it does gets generated accurately
zooming in onto the sawtooth, i think the AWG gives a reasonable accurate signal
--> to be expanded
Having SDK access is important for test automation as well as simply running some specific functional test.
Pico Technology has prepared a few video examples on how to use this SDK at https://www.picotech.com/library/videos-sdk-and-third-party-software
At first glance, there is not much documentation on how to do the programming with the SDK so i started with "brute force" attempt, just try run the examples see how they fare. upon trying, i find only this one won't have error, however not quite sure what is the AWG file format supported.
--> to be continued
The USB connector has improved over the other older version which i have used and this hopefully makes then less sensitive to vibration
It is good that it still has a 32 bit version of the software as some automation or tester project we build are meant to last for more than 10 years and there are still some that use 32 bit system. In fact
recently i have encountered a 25 years old DOS system.
Documentation on the SDK could have been slightly better in guiding new user of the SDK. However, at least there are examples