PIC16F84A Code Protect

[gatas]

Hi there...
I ve recenlty built a ludipipo-kind of programmer named jdm...After burning the chip 4 or 5 times using the icprog software i decided to use the code protect feature...After burning the chip with code protect enabled and i read it i get all the memory filled with zeros, as expected...
But when i try to erase it, change its configuration, or even re-burn it with another piece of code, things dont work....

So is the Code Protect permanent? Or there is a programmer malfunction?Shouldnt the pic be erased altough it is code protected?....

Thanx in Advance....

 

[TheAnimus]

EPROM, EEPROM
big differnce
Electrically Programable Read Only Memory.
rom that can be programed, big thing is, it can only be cleared, not set.

Electrically Erasable/Programable Read Only Memory.
rom that can be programmed, but it can also be cleared. A specail type of this memory is flash EEPROM these PICs have the F in their name
ie. 16F84A

those with a C are OTP or One Time Programable.

Hope that clears some things up

 

[gatas]

Yeah i get it...
So in PIC16F84A i can clear the Code Protect bits/reprogram it without protection, since it has a flash memory, right?
So the programmer/software is faulty, right?

Very close to understand it.....
Thanx....

 

[TheAnimus]

In a word probably
The code protection can normally be taken off by blowing the fuses again with the corespondant code protection bits off. Its also of metrit to mention that code protection only stops reads, not writes neciscerraly, so if you are storing passwords or there stuff that a cracker might want, make sure they can't add a NOP in a certain place and find the information!