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Slightly OT: AVR EEPROM Location 0 (was RE: [avr-gcc-list] address@hidde

From: Dave Hansen
Subject: Slightly OT: AVR EEPROM Location 0 (was RE: [avr-gcc-list] address@hidden ... what is it for ?!)
Date: Tue, 6 Jan 2009 16:35:51 -0500

 From: address@hidden
> Notice the starting address of eeprom is 1 byte above the physical
> address of start of eeprom because there was some rumor stating some
> models of AVR would accidentally trash the first byte under some
> circumstances. Perhaps when the rest of the device was wiped for a code
> reload or something? Anyway, it was cheaper to do without the first byte
> than to worry about it.
More than a rumor.  If you cut power to certain AVR parts during a write to EEPROM, location 0 would be corrupted.  Documented in various AVR Errata sheets. 
Limited primarily to the AT90S parts IIRC.  But it was a long while before I started using EEPROM address 0 again...

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