I suppose what I meant is that having all that code in a program would theoretically create a slower response time for data being sent to and from the I/O pins, am I wrong?
belae1ka:
I suppose what I meant is that having all that code in a program would theoretically create a slower response time for data being sent to and from the I/O pins, am I wrong?
Theoretically that is probably correct. In practice it won't be noticeable.
I sit on the fence regarding the question of whether what you want to do would be simpler with two or three MCUs or with port expansion using external hardware. If you would need to develop and debug 3 different MCU programs the balance would probably favour port expansion. But it a single generic program would do ... ?