I'm going to develop a device that I want to be able to program without removing it from the target application using the ISP functions, now from what I gatyher the programming pins can still be used for I/O ports but care needs to be taken with voltages and resistances, ok so I'm clued up on the voltage requirements/differences involved, but what about the resistance on the circuits connected to the programming pins. The pickit2 manual makes no mention of the permissable impediance that it can deal with without degrading the signal.
Any ideas ?