Down and dirty way to use a SMD PIC with a DIP programmer?

[RossWaddell]

Thanks Darrel! Can I assume that J3 plugs into the melabs U2 Programmer's socket and U1 is the clip?

[Darrel Taylor]

That's a good assumption, yes.

[Charlie]

Also note you need to lay out your board so the chip clip has room to actually clamp on the device. No decoupling caps or anything too close by. It takes more room than you think... well, more than I thought, back when they were popular. I sure didn't learn that one the hard way, no sir

[RossWaddell]

Thanks Charlie! That's good advice as I'm not very good at desoldering (even with wicks) so being able to reprogram in-circuit is critical.

[AvionicsMaster1]

As Darrel said, make sure you design to accomodate the ICSP through switches or high resistances between PIC and load. The old PBP manual had some values of resistors but I couldn't find it in the PBP3 manual after a quick search. I've experienced thinking I could program once the PIC is installed only to find out I didn't fully think it through. Good luck.

[RossWaddell]

What constitutes high resistances? All the outputs will be connected to 150-220 ohm resistors (for LEDs) but there won't be anything on VDD/VSS. And which of the ICSP connections on the PIC are the important ones for this?

[AvionicsMaster1]

If you've got a PBP2.6 manual I recollect there are hard numbers in it for isolation resistance. I thought the desired value from the old manual was several hundred kohms but I don't see it in the PBP3 manual.

If you look here http://ww1.microchip.com/downloads/e...es/_91017b.pdf it says 1kohm isn't enough. I have found an LED to ground on the PGC or PGD pins, even with current limit resistor, causes problems. I also remember that a capacitor on the MCLR pin caused a problem.

Just FYI, all these recollections may not be relevant to what you're designing. From experience I now use a switch to disconnect the PGC/PGD and depending on use the MCLR pin from the circuit for ICSP. You can get surface mount components that are very tiny.