2021-03-25 - glitching µCs

while listening to hadkaday's 110's podcast a discussion on using EMPs to glitch µCs caught my attention. along with using powerline glitches, it sounds like a great tool to trigger certain behaviors and can help with reverse-engineering the thing.

what was left open was how to make this reproducible? neither EMP generation with flyswatter nor with powerline fluctuations are easy to time properly… unless you own the time. time is not absolute for µC – it depends on the clock. so you can replace quartz / PLL with a custom clock source, that you can control. it does not even have to produce uniform square wave. you can do 20MHz for first 123456 cycles and then, when “magic shall happen”, make cycle last for seconds (or whatever else is needed).

this would be nice, as it means you can make such a hack way more reproducible.