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Pickit2 no longer recognizes PICs

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Mosaic

Well-Known Member
Odd problem,
One of my Pickit2 units does not communicate or 'see' a PIC chip, whereas the other (same cables) does just fine.
I cleared the OS and reflashed the Pickit2 but no improvement. Remelted the SMD soldering, no improvement.
It delivers good power to the Target circuit etc.
No error messages from the s'ware (latest version).

Anyone has any tips on this or do I need to go after a schematic to fix this thing and sniff the TX/RX buss.
 

Mosaic

Well-Known Member
Yes, I'd need an 18F2550 SOIC and some means to flash it. Idk if a custom boot loader is supposed to be in it to flash over USB in the pickit2.
 

Diver300

Well-Known Member
Most Helpful Member
Have you tried reflashing the PICkit2 using the ISCP connector on the inside, using another programmer?

I have had a PICkit2 delivered with no operating system that needed that to get it going. That was a long time ago when Microchip managed to ship a batch with no OS.

More relevantly, I've had PICkit2 programmers randomly loose their OS, and refuse to reflash via USB. In the thousands of times that I have used PICkit2s, I've had that happen 10 times or so, and each time I've just reprogrammed the PICkit2 using another one and ISCP.

The only other fault that I have had was when there was an earth voltage difference between the target circuit, and the PC that was running the PICkit2. That blew one of the SOT23 transistors that allows the 12 V for programming to get to the target PIC.

If you can programme the 18F2550 inside the PICkit2 using ISCP, then the 18F2550 is almost certainly fine. If that works, I suggest that you turn on the USART tool. If you link pins 4 and 5 of the PICkit2, you will get anything sent by the USART tool echoed, and no echo without the link. If that works, pins 4 and 5 are probably fine. You can also test the supply voltage on pin 2, where pin 3 is ground, to check that the voltage out is as required. Pin 1 is the Vpp pin, so that goes to 12V when programming. You will need to tell the PC that you are using a PIC that needs 12 V to programme.
 

Mosaic

Well-Known Member
I guess i can scope the Pickit2 outputs and see if the 12V is good. I didn't directly flash the 18F inside, I did that via the USB procedure. First it said no OS and then the reflash went well via USB.
 

Diver300

Well-Known Member
Most Helpful Member
If you have another programmer, reflashing the 18F2550 inside using ICSP is quick and easy, and therefore worth a try. I can't see any reason not to try that if the alternative is a new 18F2550, which would need ICSP flashing once changed.

There are parts of the code that are not changed when reflashing via USB. The ICSP flashing clears and reprogrammes everything.
 

Mosaic

Well-Known Member
Ok, a direct reflash helped.
I still had to walk thru the troubleshooting Pickit2 menu option checking the volatages on each pin and the 30Khz PGM freq etc. but after that it came alive again.

thx

flash file attached for any who need it.
 

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