16f887's dying after use, can't reprogram

Hi guys,

I have a strange problem. I am programming a 16f887 using the Wellon USB VP-Pic1 programmer. Up until recently there have been no problems with the chip, I could program it and then put it in my circuit, everything is ok, and then I could reprogram it again.

For some reason now, I can program a chip and it works in the circuit as it always did. However, as soon as I try to reprogram the chip, it erases ok but then says:

>>Erase OK!
>>.Program......
>>Device Address:000000H
>>Program fail!
>> 4.66Sec

I can put in a fresh PIC and it works fine, but once I have put it into my circuit and run it I can no longer reprogram that PIC. I am running out of chips fast and would like to know what I can do. I have tried restarting the computer, etc. and it is still the same.

There are no short circuits, etc. on my circuit. I am driving 11 transistors, 6 servos and 10 inputs via pull-up resistors. It was all working fine without problems and now I just can't reprogram.

Is there something that would cause the PIC to not allow reprogramming? Something really basic I am overlooking?

Any help would be great, thanks!

Some programmers can't reprogram some chips that have the internal oscillator selected and Mclr disabled.

Do you have a link to your programmer? Edit, found it but there is no schematic so I can't suggest anything.

Mike.

The programmer software can be downloaded from the manufacturer's site at **broken link removed**

I am using the internal oscillator however I have left MCLR enabled, and is connected to power via a resistor. LVP is off, Brown Out Reset is off also. Do you think this is just something funny with the fuses that I could fix, or is it possible my circuit could have killed the ability of the PIC to reprogram? (Or am I just using a flaky programmer?)

I couldn't make any sense of their website?, so I've no idea what the programmers capabilities are - BUT - if the programmer can't switch the PIC to programming mode before the clock starts running, then you can't ever reprogram the PIC.

It could be hardware limitations, or software limitations, I would suggest not using some obscure Chinese programmer?.

I don't know anything about this programmer, does it use LVP? Because that's enabled in new chips by default, and you say you are turning it off when you program one...?

I think the program had the MCRL set to off, and I am using the internal oscillator.

Obviously my programmer is not a very good one. If I get a better programmer will it be able to revive the PICs I have already killed? Any suggestions on a good programmer?

picdude said:

I think the program had the MCRL set to off, and I am using the internal oscillator.

Obviously my programmer is not a very good one. If I get a better programmer will it be able to revive the PICs I have already killed? Any suggestions on a good programmer?

Click to expand...

Yes, a decent programmer should be able to re-use them no problem.

The PICKit2 is really the recommended programmer these days.

Ok, I will get the new programmer. It seems other people have had this problem as well, but I couldn't find it in the beginner's guides, etc.

Thanks for the help guys.