12F675 won't reprogram or erase

[modifyit]

I just got a note back from MELabs stating that you can not reliably program the 12F675 when using both MCLR as an input and the internal oscillator.

I guess I will try making the MCLR as a reset pin later and see if another chip bites the dust.

[mister_e]

probably but as i've tons of design who use internal OSC and MCLR as i/o, i'll probably mostely bet on the CodeProtect stuff. Sure you can reprogram but can't read back. This is probably why you got this error.

ALSO, you may look at the programming sequence and idle state. Some design may ruine your life when using ICSP. Same thing for some device programmer... like PICSTART wich is still great but sometimes a pain in ICSP.

How about doing another test... remove any load on ICSPdata, ICSPClk, and place a 10K pull-up + diode on MCLR pin like...http://www.melabs.com/support/icsp.htm


Then now, remove your code protection (CP and CPD), program ir, erease it. Once done, place your load on ICSPdata, ICSPclk and redo the same... about now??? If problem persist, how about if you shut down the unit, connect it to your programmer, the power-up the unit?

Now do the same thing with the MCLR. About now?

Set your code protect.... aboout now?

[Ron Marcus]

I just got a note back from MELabs stating that you can not reliably program the 12F675 when using both MCLR as an input and the internal oscillator.

I guess I will try making the MCLR as a reset pin later and see if another chip bites the dust.

I repeat...

<<If your code is evolving, you really should keep MCLR as a reset. The last programming action will be to flip the config fuse for the MCLR pin to become an input.>>

[Ron Marcus]

Let's try that again...

If your code is evolving, you really should keep MCLR as a reset. The last programming action will be to flip the config fuse for the MCLR pin to become an input.

[modifyit]

Ahh that could make some sense then...If the last thing the programer does is flip the MCLR to being an input, that is why it could be crashing the MELABS programmer and corrupting the chip, but the chip's program seems to run fine.

I will try using the MCLR as a reset and see what happens.

Thanks again

[modifyit]

Making the MCLR a reset did the trick. Thanks to all for your thoughts