button input: what is necessary for a proofed behaviour

hello all

a bit a simple question at a first glance, but i have had some problems earlier with this....

if i have a button some centimeters or a few meters away from a pic, what would be the best method to connect this? try to avoid all environment influences..

perhaps to route out the ground to the button, and the input side with a pull up (10k?) to the pic? a capacitor (value, typ?) from the input line to ground? a 100 ohm resistor in serial to the input line near by the pic? (i have sawn this recommendation in a microchip app note in relation with a keyboard once, but i am not able to refind this document again....)

thanks for some hints or links to other threads

cheers

mmm, well there's many different method from the opto coupler, to the funky MAX 232, to the current loop, to the simple 'just extend your wires - but do a software compensation method' and finally, use 2 i/o : one to send a query to the button, and the other to read it.

Which one is the best? i think this might be different from an environment to another. (HV or not)