My home controller system is spreading all over the house...
The GPIO outputs all go via fairly short leads to driver boards, but the inputs come from buttons and other sensors up to 10m away, and now I need to go even further.
Most long cables go to simple buttons, or mechanical relays (e.g. in PIR motion detectors.) All are configured with an internal pull-up resistor. I am about to add some electronic PIR detectors that have a direct 3.3V output; they came without specs, so I don't know how far they can reliably go, but that is another issue.
So far everything seems to work ok. Is there anything I should be doing to protect the inputs from damage or to filter out noise? Should I be using opto-isolators?