ISP with Picckit2

[Thunderchild]

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 ?

 

[Nigel Goodwin]

If you need to use the pins, them make sure you use them for functions that will obviously have no effect on ISCP - such as switches with high value pull-up's. If you study the circuit of the PICKit2, you will understand what it's capabilities are likely to be.

 

[Thunderchild]

yes well I did have in mind (I've now moved things around) that there would be just resistors in parallel with the ISP pins so was wondering what actual resistance the pickit2 could handle. I've now made this so that the ISP pins are also port pins for external/diagnostic functions (when I get around to putting them in) so I'll have a port for both programming and interfacing