Does anyone know of an MCP23017 library which can support chip(s) configured as outputs plus other chips configured as inputs that give interupts for both 'Offs' and 'Ons'?
It doesn't necessarily have to be a library, a stand-alone sketch giving that sort of functionality would be very welcome.
Basically I wish to monitor more than 20 door switches for being triggered when opened or closed, and be able to control several things in response.
There seem to be plenty of examples which can do one thing or another, but I haven't yet been able to find anything that can offer rising and falling interupts AND manage multiple chips. The Adafruit library seems professional, but I can't find an arduino tutorial for it (only for their Ras Pi/ Beaglebone version), and in the arduino examples there is no mention of using multiple expanders, plus the interupt example suggests interupts are generated only when input buttons are pressed and not when they are released. The Centipede library can handle multiple chips as inputs and outputs, and mentions a forthcoming interupt version, but it was promised long ago, and I can't find it.
Does anyone know of anything suitable, please?