Glitch crowbar output always shorted?

I want to use the crowbar on the CW1200 for glitching, but I’ve noticed that the crowbar glitch SMA output is always shorted, even when the CW1200 is turned off from both power and USB. I verified this by measuring the continuity on the SMA pin, and it seems that it has a direct connection to ground. I measure 1.8 ohms.
How is this possible?

Also, I’m observing a strange behavior from the CW. If I do:
scope = cw.scope()
scope.clock.clkgen_freq = 100e6
scope.glitch.clk_src = ‘clkgen’
scope.glitch.trigger_src = ‘manual’
scope.glitch.output = ‘enable_only’ = True = False = 10

The “Glitch Trig’d” LED stays ON, even though the counter of glitches says at 10. If I set glitch.repeat=1, this behavior doesn’t show: the LED blinks once as expected.

Thank you!

1- Definitely not normal; have you been using this with a target and is it working normally? Possibly you’ve run into this: CW1200 ChipWhisperer-Pro - NewAE Hardware Product Documentation

2- That is a harmless bug; it does not mean that the glitch is still being applied. You can turn off the LED by setting scope.glitch.repeat = 1 (and then back to its previous value).

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So I’ve done an experience now:
Turned off the CW, measured resistance on the Crowbar Glitch SMA out, I see 1.8 ohm.
Then turned on the CW, and set it to scope.glitch.trigger_src = ‘continuous’. I measured the SMA during this period and it seems to measure 0 ohm.

Could you try to measure the resistance you have on your glitch out SMA pin, with a multi-meter, while the CW is off, and let me know if you have something in this low range of 2 ohm ?
I’m using the io.vglitch_reset() function so this should not be the problem.

This is my first time using this CW.
Thank you!

I get around 2 megaohms.
I’m wondering if you may have damaged the glitch MOSFETs, e.g. possibly while trying to glitch with a too-high clock frequency as per your other post.

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That’s indeed different. I’ll try to check if it’s the case that the MOSFETs are damaged.

Thanks for the information!