Hi everyone 
We have been working with multiple ChipWhisperer Lite devices recently and we noticed an odd behavoir of one of them after performing several thousand captures in a row.
Some context:
- We are working with the ChipWhisperer Lite, CW308 UFO Board, and the STM32F3 Cortex-M4 Target (three times the whole setup)
- We are tracing schemes that have cycle counts in the millions and thus for only one “complete” capture we are required to perform ≈100 partial captures of the same scheme (therefore, high offsets are required). This means we want to perform a large amount of captures in a row.
The problem:
With two of the three ChipWhisperers everything works fine. But one of them occasionally displays “WARNING:ChipWhisperer Scope: Trigger not found in ADC data. No data reported!” directly followed by “ERROR:ChipWhisperer Scope: Received fewer points than expected! 0 vs 24400”.
The error mentioned above does not occur during the first ≈5000 captures (this is varying a lot) but at some point it will start to occur and the frequency of the error increases until almost the majority of captures fails.
What we have tried/learned so far:
- This error is not caused by any of the other parts involved in the setup: We tried interchanging the UFO board, the target, the cables, USB ports etc. So we think it is in fact related to the ChipWhisperer board itself.
- When pointing a fan directly onto the “faulty” ChipWhisperer the errors do not occur. This is what made us think we might be dealing with a temperature issue. Since the ChipWhisperers are located inside a server room with an AC, we think the ambient temperature should not be an issue.
Our questions
- Have you ever had to deal with similar issues?
- Might this be an indication for a hardware issue of the ChipWhisperer board? (it showed this behavoir right from the beginning)
- What can we do about this?
Thank you for reading my post!
Kind regards
Amin