12F programming woes

[Ron Marcus]

I am trying to program the 12F series with a MElabs U2 programmer. These are new parts, 12F635s and 12F683s.
First of all, the programmer tells me that the devices have the wrong IDs. Next, when read, I get all 0x00s. I tested the programmer with the 16Fs and it works fine.
The 12s were not previously programmed, and I was careful to set config to RESET the MCLR pin. There is nothing else attached to the chips. I downloaded the latest Meprog software and firmware, but still no go.
This has got me stumped, but I am sure there is some logical explanation...
Any ideas?
Thanks,
Ron

[mister_e]

I don't have that programmer myself but, if you have some decoupling cap close to your PIC, and use their schematic for ICSP, or use their dip adapter + decoupling caps ... I think you should contact Melabs for that :(

[email protected]

Usually they reply within the same day.

[Bruce]

Are you using a ZIF socket or programming in-circuit?

If you're using the 8-40 ZIF socket, make sure you have the programmer plugged in
to the 8-20-pin header on the adapter, and pin #1 on the 8-pin 12F PIC by where it's
marked Pin 1: 8-20 on the adapter.

[Ron Marcus]

Are you using a ZIF socket or programming in-circuit?

If you're using the 8-40 ZIF socket, make sure you have the programmer plugged in
to the 8-20-pin header on the adapter, and pin #1 on the 8-pin 12F PIC by where it's
marked Pin 1: 8-20 on the adapter.

I am programming in circuit. There is no other load on any pins.