PIC16F628A code protection

Question is which programming voltage the programmers you have tried use?. Once the protection fuses are set, a full erase, using a programmer that support the high voltage programming algorithm, is needed to once again access the chip.

Best Wishes

Hmm, you should be able to erase it. You're not using low voltage programming (LVP) are you? I believe you have to use a programmer that supports traditional (HVP) to erase it.

Hi,

Thanks for the information.

I am using High voltage programming (12V) and the supply voltage is

4.85V. Does the PIC tolerate such deviation from the supply during programming?

Joseph

I'm not sure what you mean. 4.85V is close enough on the 5V supply, but Vpp should be close to 13V IIRC. Is your programmer applying that much voltage to the /MCLR pin when you program it?

"joseph" schreef in bericht news: snipped-for-privacy@p10g2000cwp.googlegroups.com...

You need a HV programmer that can supply the required high voltage. If memory serves it is 13.5V for the PIC16F628A. You can find the programming specifications at Microchip. Code protection fuses need more power and time to be erased then the others. Which is deliberately done by design to make sure all others are erased before the code protection fuse is. Make sure to select the right component on your programmer. The programming algorithm of the PIC16F628A differs from the one of the PIC16F628.

petrus bitbyter

Did you pulldown the PGM pin? Just in case the famous and unpredictable conflict between LVP and HVP is not the culprit.

Octavio

Sounds like this problem:

but it depends on what config fuses and what programmer you're using