PIC won't take new code

[heida11]

I have several 16F628 PICs involved in a project.

One of them suddenly stopped taking new code. Also cannot erase whats
currently on the PIC. The remaining PICs are programming just fine.

Would appreciate any ideas on how to resolve this.

Thanks

 

[ivancho]

Where you handling them with care? Perhaps some static electricity just zapped them :?

 

[Nigel Goodwin]

What software are you using to program/erase them?. If you've got them set to use the internal oscillator you need to switch them to programming mode very quickly - before the oscillator can start. My software WinPicProg incorporates a Vpp delay, and if it's set too high the oscillator can start and this prevents programming the chip.

 

[StupidDum]

DId you check the "Code Protected" in MPLAB configuration bits?
That shouldn't be on

 

[heida11]

Nigel,

I bought the P16PRO40 with a 74L506 pre-assembled, but don't know
how to set up the hardware so I inverted the last three (attachment)

The program LED doesn't lite when trying to program a PIC so have been using IC Prog. (It inverts output, clock and input)
I also installed the Port95nt driver.
I use Win XP.

Would like to use your program if I could determine how to setup the
hardware.

I do use the internal osc & the protected mode is off.

 

[heida11]

Nigel,
Found picallw and configured P16PRO40 per its example and your winpicprog works now.

This one PIC still won't give up it's code nor allow new code to be programmed. I am putting it away and moving on to purchase a new one.

Thanks to everyone for your input, I have used everyones suggestions but that PIC has a mind of it's own!!!

 

[Nigel Goodwin]

Nigel,
Found picallw and configured P16PRO40 per its example and your winpicprog works now.

WinPicProg has fixed settings for both versions of the P16PRO40, simply select the one you have from the pulldown menu - you don't need to use the custom settings.

This one PIC still won't give up it's code nor allow new code to be programmed. I am putting it away and moving on to purchase a new one.

Have you tried reducing the Vpp Delay to zero?, see if that works.