Flash write problem on PIC18F2523

[Hamid]

Hi,
I want to write data to flash same as eeprom but I have a big problem when I write new data the result LOGICALLY and" with the privious data ?? its mean I can not change the 0 data to 1!
how I can write new data to flash without this problem?

[Ttelmah]

This is a function of the flash memory. It is erased in _blocks_. The function 'write_program_memory', will only erase a block, when you write to a block _boundary_ (first byte in the block). Look at the manual, for 'write_program_memory'. There is a table at the bottom, which descibes when the functions will erase a block. The 'write_program_eeprom' function, will only erase on chips where the erase size, matches the block write size.
If you want to change just an individual byte or a few bytes, inside a block, then you need to read the whole block, change the bytes in the read values, and write the entire block back.

Best Wishes

[HAMID]

THANK you a lot