Blowing up PICs left right and center

[George]

Managed to get my PICkit 3 reprogrammed with new firmware - my USB port didnt have enough supply to power the unit while upgrading firmware - used another port and worked a treat.

However I've tried now programming with out code protect so specified _CP_OFF, same deal - identified device fine, programmed it, device works as programmed however I still cannot erase it etc - i just get this:

Erasing...
Erase device complete

Blank Checking...
The following memory regions failed blank check:
Program Memory
Address: 00000000 Expected Value: 00003fff Received Value: 00000000
Blank check failed

then if I try to reprogram it, I get this:

Programming...
The following memory regions failed to program correctly:
Program Memory
Address: 00000000 Expected Value: 00002860 Received Value: 00000000
Programming failed

If I shut the MPASM down then restart and plug in my micro I'll get:

Target Device ID (00000000) does not match expected Device ID (00001060)

[George]

Ok, I've had a good look around the internet and have found many people have had experiences similar to mine when using PIC16F628A, some people have found a cure that works for them but nothing at this stage seems to work for me. Neither my PICkit 3 nor ETT programmer will recognize the PICs after they've been programmed, neither will they do anything to them - ie erase. I've tested the VPP while erasing and it runs up to 13.4 volts four times for a period of about 20ms.

I've turned code protect off, i've turned MCLR on, have tried different programming voltages but now I just have 15 PIC16F628 chips that I cannot write to.

It's getting so frustrating, if not for the cost of the components, but I've spent four whole days on it so far and gotten no where. I think it's likely to all go in the bin soon.

[Jerson]

George,

I'm not sure if I can be of any help since I've never faced such a problem. However, have you tried calibrating your pickit3? I do not have a pk3 but, in the pk2 there is a calibrate function where you can set up the voltages accurately. It is under Tools->Calibrate VDD and set unit id on the pickit2 software.

Maybe the VIHH needed for programming the part is off?

Best

[George]

Thanks for that, just this very minute got it sussed, so hopefully this will help someone else out facing the same problem. BTW is appears PICkit 3 does not have the same calibration function as #2 - but will fairly accurately provide feedback of the voltage.

The issue resolves itself on both of my programmers if I force the programmer to hold the device in reset.

I did a conversion to a PIC16F88 to see if it was just the 628 playing up, however the 16F88 did the same thing so it must be something to do with my CONFIG system setup or hardware that's a bit quirky. Looking over the net there are many folks that have had the same problem, but none of the solutions I saw suggested to hold the pic into reset.

Hallelujah!!!

[kellyseye]

Happy to hear of your solution to the problem.

Have you retried the 'dud' PICs to see if they are resurrected using this technique?

[George]

yes, have managed to erase the 'dud' chips, there is a technique - like plug them in, activate hold on reset, unplug then plug in again and erase twice - but it works at least!