ESP8266 Community Forum

THANK YOU! I spent two days trying to get to the bottom of random resets -- capacitors on the power, swap out ESP devices, disconnect all connected hardware -- nothing stopped the resetting. Finally, disabling timer interrupts stopped the resetting (thus indicating that interrupts were the problem) and adding ICACHE_RAM_ATTR to the timer ISR service routine allowed me to use interrupts without random resets.

It's apparently a very important and poorly documented compiler directive.

Norm