Thanks for that, appreciate you took the time to reply. Your example uses a timer in the main file like my first example above. I can get this to work fine and I've written esp32 timer interrupt code for other projects but the code has always been in the main file. Today I thought I'd keep things a ...

This may be my inexperience but I'm getting a 'hw_timer_t' does not name a type error when declared in an included file. I've stripped the problem down to very simple files. (All using the Arduino IDE for ESP32 Dev Module), if I have this simple file; hw_timer_t * timer = NULL; void setup() { } void...