Managed to ‘brick’ a couple of Xiao ESP32C3s at the heart of the robot. Had one spare remaining, commented out the offending code (timer exceptions – dark art though that’s another story). Anyhow, to ‘unbrick’ the others I believe this is the procedure:
- Use esptool with a “–no-stub” argument to upload dummy code – see these comments.
- Update the bootloader – see factory reset. [May not actually be required? Worked here. Also “hold boot button, press reset button briefly, then release boot button” to get a COM port afterwards?]
- Flash the ESP32C3 memory – see how to erase flash.
- Upload (in this case) micropython again – see micropython on the ESP32C3.
- Don’t forget to ‘reset’ the ESP32C3.
Can’t exactly remember the order of the above so PLEASE do experiment! 🙂