Which pin caused interrupt?

Firmware
1

I have several pins attached to the same interrupt handler:

attachInterrupt(pin_1, interrupt_handler, CHANGE);
attachInterrupt(pin_2, interrupt_handler, CHANGE);
attachInterrupt(pin_3, interrupt_handler, CHANGE);

Since I can’t do something like pass an additional parameter to the interrupt handler:

attachInterrupt(pin_1, interrupt_handler(1), CHANGE);

Is there a way to figure out which pin caused the interrupt inside the handler?

2

AFAIK, not really since the system does clear the HW flags (and introduces ~1µs+ latency) prior calling your handler .

The easiest way would be to donate one ISR per pin to register which pin actually fired and from that ISR you can call a generic function that does the common jobs.

3

Or, sample the pins (using pinReadFast() for example) to see which one changed, causing the interrupt. This will require that you maintain the previous pin states.

4

and that the trigger pulse is considerably longer than the interrupt latency (>5µs should do)

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