Checking a thing about interrupts

Question

If I disable interrupts (for example noInterrupts or cli) and enable them (interrupts or sei for example) later, would interrupts which would have executed in the window in between fire by the execution of the latter? I guess not, and haven't confirmed or denied it. If not it is always an option to manually disable timers or components with similar concerns with respect to the interrupt status? It makes sense that AVR-based Arduino boards would behave similarly. It seems plausible that the bits for the force interrupt execution will turn on and turned off when the jump occurs. Thanks for reaching out.

Answer 1

See How do interrupts work on the Arduino Uno and similar boards?

Yes, most interrupts will be remembered and the ISR will be executed when interrupts are enabled again, plus one more instruction has been executed. If that didn't happen it would be very bad, as you may turn off interrupts briefly and you wouldn't want to miss the thing that the interrupt was for (eg. incoming serial data).

To stop that happening you need to clear the "interrupt has happened" bit for the individual interrupts. This is documented in the datasheet for each interrupt.

The order in which outstanding interrupts will be serviced is the interrupt priority, that is lower-numbered interrupts will be serviced first. The call to the ISR causes the processor to clear the "interrupt has happened" bit for that interrupt.