wvmarle:
Won't work too well if you have many buttons pressed all over the time, or more than one button press at the exact same time.
No this won't be an issue, however I will also have a display the MCU needs to feed. I should probably use a second µc for that purpose or do you think the main one can handle that ontop of scanning such a huge matrix?
wvmarle:
So instead you wait for an interrupt to come in telling you something has happened, scan which of the 8 ports has the interrupt, work your way up until you find which group of 8 ports has a button pressed, and then scan those 8 ports to find the activated input. This process shouldn't take more than 1 ms depending on the speed of the I2C bus.
What frequency can I expect from encoder outputs? It has 24 positions and perhaps I turn it half way round in one go thats 12*2 positions in I guess something like 200 ms, perhaps I'll have this input on two encoders at once so I'll probably want to make sure I do indeed have a rather fast I2C bus that can scan the matrix in 4ms at the very least, what do I need to look for to make sure this happens?
Also come to think of it, this amounts in 4 inputs at a time, can I even scan for 2 interrupts at the same time?