External Glitch Trigger


#1

I have a CW Lite and would like to use a power probe to trigger the glitch attack against my target board. Manual trigger tests show me that my voltage glitching is successful. I now need to glitch at a precise time. I’d like to trigger the glitch sequence when a certain voltage threshold is crossed from power probe measurement readings.

I understand the CW Lite has an external trigger input pin. It can also measure the voltage values from the probe. Any suggestions on how I would go about setting this up using either of those inputs?

I also see that the CW Pro has a SAD trigger. Would I have to move to that and adapt my trigger to a SAD window?

Thanks,
– Brian


#2

Hi Brian,
CW Lite only supports triggering from the digital trigger input.
But yes, you can do what you describe with the CW Pro; see https://wiki.newae.com/CW1200_ChipWhisperer-Pro#Advanced_Features and https://wiki.newae.com/Tutorial_A4_SAD_Trigger_for_SCA_and_Glitch.

Jean-Pierre


#3

Thanks for the response Jean-Pierre. Is the CW Pro able to do triggering much like an oscilloscope, given an edge and threshold, or is SAD the only trigger option? I haven’t thought SAD triggering through enough to know how good it is at edge detection.


#4

Good question; since the SAD pattern width is fixed at 128 samples, you won’t be able to have it trigger on a single specific voltage reading. However, if the trace characteristics that lead to your desired trigger point are consistent, then the SAD trigger should work well. But I don’t have any experience actually doing this myself.

If the SAD doesn’t work for you, then you could modify the CW to do exactly what you want, since this is all done in the FPGA. Should be straightforward but requires familiarity with Verilog and the Xilinx toolchain.

Jean-Pierre