PPK2 missing samples depending on DUT

RE: PPK2 missing samples depending on DUT

user75734 — Fri, 20 May 2022 10:38:16 GMT

I just spoke to one of the developers to confirm my suspicion, and yes, there are a few samples that will fall out as the voltage range is switched, as these samples will come out invalid. There is also a counter in the payload that should make sure the SW corrects itself if samples are lost between USB and SW handling.

Best regards,

Simon

RE: PPK2 missing samples depending on DUT

user116254 — Thu, 19 May 2022 08:50:11 GMT

My software configures the PPK2, starts the measurement, and logs the raw data into the memory. At the end of a run, I go through the data and have a look at the counter which is part of each sample.

According to https://github.com/NordicSemiconductor/pc-nrfconnect-ppk/blob/main/src/device/serialDevice.js a sample is 32 bits long and consists of the following data fields:

31 : 24	23 : 18	16:14	13 : 0
Digital Inputs	Counter	Range	Value

While inspecting my data I see missing counter values in all variations from one missing sample to 63.

So, if I understood you correctly, you think that the MCU software is skipping samples if there is a change in the shunt value?

Regards,
Johannes

RE: PPK2 missing samples depending on DUT

user75734 — Thu, 19 May 2022 06:57:06 GMT

What exactly does the software you've written do? Is there a reason you're not using the Power Profiler app in nRF Connect for Desktop, or are you? I don't see why you would be missing samples depending on what the application is doing. The only thing I can think of is that the PPK2 is prone to some current spikes when switching between the voltage shifters, which your software might write off as "missing samples"?

Best regards,

Simon