The Chipwhisperer creates a Sawtooth course with a period of about 1 min.
I created a similar topic a few days ago “Sawtooth course of Single Point of Trace - ChipWhisperer LiteArm” but with further investigation i became further results.
I tried a lot of different capture settings:
- gain.db = 25
- adc.samples = 600
- clock.adc_src = “clkgen_x1”
(changed the settings directly in the library)
The reset of the settings is default.
I executed 500 “nop” instruction and and took the mean of the Power Trace, this i have done for 20000 Traces.
import numpy as np
import matplotlib.pyplot as plt
traces = np.load(‘traces.npy’)
trace = traces[:, 20:500]
trace1 = np.abs(trace)
mean = np.mean(trace1, axis=1)
Plot of a Single Power Trace:
Mean of Power Trace over 20000 Traces:
With a second Chipwhisperer LiteArm I became the same results, so it should not be a defective hardware.
For a test I also added some delays inside the capture script and noticed that the period became smaller (less traces per Period) so it has constant time.
I also tested it with a Chipwhisperer CW303 with the same setup, there i do not get the sawtooth course.
CW303 Mean of Power Trace
I added the Src-files as an appendix
Thank you for your help.
srcfiles.zip (2.2 KB)