Situation: You want to include a timer interrupt service routine in an assembly language program for an AVR-based Arduino. The program will be written, assembled and uploaded using the Arduino IDE.

I have a 3rd party library that checks whether digitalPinToInterrupt() returns NOT_AN_INTERRUPT, which isn't defined in this core. Clearly, all Pico pins are interrupt-capable, but it would still be ...

but instead I found such an thorough and well thought-through answer on StackExchange that I thought I had to point it out. So, t0 the question: What is AVR Arduino interrupt latency? And how can it ...