I’m using external GPIO to set the trigger and my target is running at 204Mhz. I able to glitch the code similar to glitch1() code with voltage glitching with Repeat set at 204 and Ext Trigger Offset at 6 (using Enable Only mode). My question is why is the Repeat has to be 204 or larger? From the code that toggle the GPIO for the trigger to the while( a != 2) there should only be around 6 instruction clock cycles. So what are the unit for Repeat and Ext Trigger Offset parameters. It doesn’t look like clock cycles.
I agree that there should only around 6 instructions from trigger_high() to the first branch in the loop, so it’s a bit crazy that you need a repeat of 204. These numbers really are clock cycles.
One possibility is that the voltage glitching often takes a decent amount of time to have any effect. If you’re connecting the glitch output to your target through an SMA cable (especially if it’s long), you may find that short glitches won’t do anything - if you only use a few microseconds of glitch output, the MOSFETs are too weak to drain enough current from the target’s capacitance through the cable’s inductance. This means at high clock speeds, you need a very high repeat count for the glitches to work.