ChipWhisperer-Lite (CW1173) and oscilloscope


#1

I have a few questions regarding connecting an oscilloscope (using the schematic found here) to CW-Lite. Soldering some pinheaders (or connectors) as needed is not a problem.

  1. Where on the CW-Lite board (PCB) can I connect an external coax trigger signal output from my oscilloscope? Want to let the oscilloscope handle triggering.

  2. Are there any points on the CW-Lite board where I can hook up an oscilloscope with passive probes and use the CW-Lite ADCs as a “diff probe” with the CWCapture program running?

  3. Instead of breaking off the Device Under Test (DUT) board, is it OK to just remove solder bridges SJ4 and SJ5 to use external target? Assuming I can just use pinheaders with jumpers on JP7 and JP6 to enable/disable the internal target as needed then.

BTW: I’m impressed with the design, software and tutorials so far, learning a lot, thanks.


#2

Hi modrobert,

(I am not the expert here but trying to answer while learning stuff)

  1. (triggers)
  • The CW-line only allows for IO triggers. there is no need to use a coax or similar for external trigger.
  • The trigger and pin used are configurable. I don’t think there currently is a single point dedicated to deliver an external trigger (this might be fixable in software)
  • Depending on the quality of your oscilloscope you might want to reverse things around (trigger using the oscilloscope and lead the signal to the CW)

2(oscilloscope)
If I understand correctly you would like to reuse the analog part of the CW-lite and connect this to an oscilloscope. “as differential probe”

The CW lite does not work as differential probe (you still measure the voltage between ground and the measure point but there is a DC blocking cap) so you can strictly speaking not use the CW as differential probe.

If you want to do this is it perhaps a better idea to buy the differential probe (and power supply)
store.newae.com/differential-pro … led-tested

3(DUT board)
I don’t know I think it would be better to split the board.


#3

Yes, that’s what I asked for, but specifically, what point (or range of points) on the CW-Lite board (PCB) can be used? I found a point labelled [TRIGOUT], but that’s the opposite then.

Actually, I think it can work as a “differential probe”, but perhaps there is no easy/direct way to connect the oscilloscope to utilize it. Maybe my terminology is off, just looking for a way to see the results both on the oscilloscope and the CWCapture GUI, as seen in Tutorial B2:

wiki.newae.com/Tutorial_B2_View … Adjustment

Perhaps just connecting the oscilloscope to the “MEASURE” point on the board would achieve that?

Well, after checking the schematics and board visually, why go through the trouble of creating solder bridge pads and plated through-hole for use with pinheaders and jumpers then? If I understand it correctly, after removing the solder bridges SJ4 and SJ5, the target (DUT) can be enabled and disabled with two jumpers then (JP7 and JP6). I kind of like the idea of having the XMEGA128D4 readily available for hacking purposes.