how to reprogram 12f675 and 12f629 ?

[iw2fvo]

hi to all of you in this forum,
I programmed some 12f675 and 629 and I reassigned the pin that are normally used for programming the chips.
MCLR, PData and PClock do not have their function anymore.
I have to reprogram those chips but the PicKit_3 does no longer recognise the chips. So they bicame like an OTP !!!
I follow some instruction found on the net and suggested in the forum but with no success.
Any proven procedure available to recover the chips please ?
Thanks in advance.
regards,
Ambrogio

[mackrackit]

I will guess that you have the chips in circuit and the three programming pins are connected to something.

You will need to disconnect the three pins or in some way isolate them from the remainder of your circuit.

Then you should be able to re-flash them.

[richard]

vcc may need to be 5v also , and sometimes its best to let the pickit provide the power

[iw2fvo]

Thanks,
The three programming pins are connected to the PicKit only.
The 5vdc is applied to the PIC by the circuit : PICKit does no suuply power to Pic.
No way for now to recover them.
Bye
Ambrogio

[iw2fvo]

I forgot to say that I have read and applied those instruction:

http://www.microchip.com/forums/tm.a...&mpage=2&key=&

Ambrogio

[richard]

PICKit does no suuply power to Pic.

that's my point , the pickit needs to provide the power . timing is critical in getting the chip into programming mode