AVR-Chat

On Apr 27, 2008, at 1:49 PM, Don Kinzer wrote:

> --- In AVR-Chat@yahoogroups.com, David Kelly <dkelly@...> wrote:
>> EEPROM is writable at the byte or word level
> As an aside, I believe that EEPROM is also organized in pages but the
> processor takes care of the read/modify/write process (if required) so
> that it is mostly transparent.

I've never seen EEPROM that emulated SRAM as you suggest. Writing  
EEPROM generally isn't terribly complex but its definitely a  
deliberate process.

IIRC the EEPROM in HC11 is inverted, erases to 0x00, but generally  
EEPROM erases to 0xFF as in the AVR. Each erase is half of one count  
toward the life of the memory. Toggling a bit from 1 to 0 is the other  
half. On the HC11 I had selective control over which bits in a byte  
were erased. On AVR one doesn't have that control, the entire byte is  
erased as part of the write. Don't know if "erasing" a 1 applies wear  
or not.

Have also used Atmel Dataflash on SPI. This is a different animal than  
the FLASH or EEPROM on an AVR. The Dataflash has an internal RAM  
buffer. All writes copy the entire buffer to the designated page.

--
David Kelly N4HHE, dkelly@HiWAAY.net
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Whom computers would destroy, they must first drive mad.