Problem with WRTD Fuse

[kt1]

Hi all,

I'm trying to protect the eeprom on my 18F2220 rev b2 from external writes. I enabled the WRTD fuse, but this prevents the PIC from writes to eeprom using write_eeprom(), i.e. no matter what I write to it I get back 0xFF. Everything works fine when NOWRTD is set. The datasheet states that internal writes are enabled regardless of protection bit settings. What is the expected behavior of WRTD?

Thanks,

Larry

[mvaraujo]

What do you mean with external write? Removing the chip and programming externally?

[kt1]

mvaraujo, the microchip datasheet explicitly says external write, so I'm assuming that there is a way to write to the EEPROM other than through the PIC, but I'm not sure how. I guess I should ask how can one write to the PIC's EEPROM other than through the PIC's intructions, i.e. write_eeprom(), and how can I eliminate this from happening.

[Mark]

[Guest]

Answered!