debug module pin for IO

[sadlpx]

My project is using a 28 pin pic. I'm short two pins and don't want to go to a 40p device. What special considerations or hardware could i or should i use to make the 3 debug lines dual purpose.

[ckielstra]

I recommend reading the ICD2 and Pickit2 manuals on this subject.
I also like the ICD2 Poster which gives some extra 'Target Circuit Design Considerations'.

I guess you make things easier to yourself when you choose the PGC and PGD pins as outputs in your application. Just make sure that normal signals generated by the debug unit will not trigger any unwanted side effects (launch a rocket, etc.), i.e. choose an output function that by itself is harmless. Note that you can't place pull up resistors on the PGC / PGD lines, but pull down >10k is allowed.

Consider upgrading to a larger package. From past experience I have learned that a new design will always get asked for more features in the near future. Best practice is to design with about 10% of the pin numbers free for these future features. Configure unused pins as inputs and add a pull down resistor to avoid oscillation.

[sadlpx]

Thanks I had not seen that poster, this will solve my problem. I have 2 leds that i can move to the debug pins. function not important till later.