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Adrian McEwen

Back on our hand-decoding USB from oscilloscope traces schtick.

@huffeec pointed out that they're Start-of-Frame packets rather than NAKs. (People who build protocols sending packets least-significant-bit first are even worse than those who use little-endian!)

At least now I (think) we're getting somewhere. Looks like the ESP32C3 is ignoring the computer for some reason.

An oscilloscope trace showing the tail end of one USB packet, a momentary pause, and then the start of the next one. That's indicated by two traces overlaid, which broadly show assorted square waves: one for D+ and one for D-, when they flip that shows a 0 and when they stay apart it indicates a 1; when both traces drop to their lowest points together that indicates the end of a packet. A couple of white cursor lines are also shown - they're set three bits apart to help as we scroll through the trace decoding the individual bits to then turn to bytes and then to USB packet types.
#weeknotes#ibal234#ESP32
Dec 24, 2024, 12:39 PM·Public·Web
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