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Re: [avr-gcc-list] EEPROM Locked?

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] EEPROM Locked?
Date: Tue, 26 Mar 2002 11:21:25 +0100 (MET)

"Tinggo - Santoso" <address@hidden> wrote:

> Is it true that if I Lock my 8515 for both level (Lock Bit1&2) then
> the Internal EEPROM is also Locked and becoming Blank? Or,maybe it's
> blank if it's seen from the Programmer but it's not Blank when it's
> seen from the Internal Program?

The latter is the case.  If you program both lock bits, you cannot
read the EEPROM from within the programmer, but of course the program
itself still can read (and write) it.

However, it should not appear as `blank' to the programmer (which
would mean it displays as 0xff), instead it should read out with
values equal to the address (i. e., EEPROM address 0 reads out as 0,
address 1 reads out as 1, etc.).  In the programming algorithm, a
locked device will always echo back the given address value, in the
bit places where an unlocked device would return the memory contents.

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/
avr-gcc-list at http://avr1.org

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