Thanks for your help - I'm getting somewhere now, but still having some issues.
I can read inputs ok and, when I change an input state, I can read which input changed from:
ReadInterruptStatus(0) and ReadInterruptStatus(1).
However, the INT output pins never change state.
I currently have:
The INT output is connected to a GPIO pin, which remains permanently low (or high if I set SetInterruptPolarity(1)).
I presume I'm still missing something somewhere.
I am wondering whether I need to use this command, but not sure how as I am wanting the INT pin to trigger on input going 0 to 1 or 1 to 0:
SetInterruptDefaults(byte port, byte value)
These bits set the compare value for pins configured for interrupt-on-change on the selected port.
If the associated pin level is the opposite from the register bit, an interrupt occurs.
Parameters: port 0 = pins 1 to 8, port 1 = pins 9 to 16, value: compare value