Not strictly a PBP programming question but I hope not too far off topic for someone to offer me some advice. I'm planning a conbined lap counter/timer and will be selecting 6 or 7 functions by earthing normally held high pins (pull up resistors) on the PIC. The selection will be made on a small portable control panel 6 or 7 metres from the main unit and PIC, wired down a multicored cable. My question is...is it acceptable to earth PIC input pins at this distance or is it either mandatory/safer or wiser to earth say via local optical isolators, controlling these from the control panel.

Some advice would be gratefully received

Thank you

Adrian