PicKit2: Beyond 20pin via ICSP.... Right ?!?!?

I have successfully created a replacement board for the demo that comes with the pickit2. my board supports the same chips as the original, only it mirrors ALL of portc to LEDs as well as portb. also, it has a second DIP socket intentionally left empty, to which all pins are mirrored. This makes for easy probing of the sockets for which i do not have LED indicators. make sense ? the important thing here is, i rigged it up, slapped on a capacitor, and it works. EVERY TIME.

then i tried the same thing for a 28pin. pin1 is VPP, 8 and 19 are VSS, 28/29 are icspdat/clk, and pin 20 is vdd. Simple enough. I've tried every possible VSS combination, with and without capacitance (At various levels) at best my pickit will see the 16f883 i am using

60-70% of the time. it seems to like seeing the chip every other time i try. I've read the docs on the 883, on ICSP, and i've taken a look at Microchip's schematic for their 28pin demo board. But alas, i am missing something.

What in the living hell am i missing ? Honestly, i'm starting to think my pickit is damaged/faulty. Oh, by the way, i've tried 3 different 883s in the unit, 2 of which had never been touched before this AND i was careful about static and whatnot.

I'm hoping this is something stupid on my part. Thanks in advance.

Reply to
mcnerd
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I connected pin6: PGM/Aux on a whim, and it seems to be behaving much better. I thought i remembered reading somewhere that this was not needed if i wasnt interested in LVP... Oh well, Let's hope that's all it was.

Reply to
mcnerd

One issue I just ran across while prototyping my PIC programmer on some perfboard (basically the Tait design,with a few tweaks) was that I was getting errors about 40-50% of the time,when writing to a chip.. reading it back worked perfectly,every time,once the chip got programmed without errors.

The Data and Clock lines DO NOT like to be run parallel to each other. After some re-routing of wires,all is well 99% of the time. Keep the traces/wires for Data+Clock short and neat.Don't run them next to each other,or next to any other random signals. Layout can make a difference!

Reply to
PhattyMo

I will certainly put this suggestion into action. definitely helps explain my much higher success rate on a SBB.

what i am experiencing now is that if i have the LVP pin connected and vpp disconnected, the chip is always seen. if both are connected, it is seen only half the time.

Reply to
mcnerd

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