At 07:15 PM 9/27/2005 -0500, you wrote:
>Hi all,
>
>I'm storing data (3 bytes per data-set) into EEPROM, and I need some way to
>later validate that none of the bytes are corrupt.  So I'm investigating
>checksums, raid, etc.
>
>Haven't found much info on checksum algorithms that would be useful for this
>simple application, or more importantly how to develop a good checksum
>application for just 3 bytes.
>
>But I've got quite a bit of EEPROM space at my disposal now (using a serial
>EEPROM), so wondering if it would be better to skip the checksum computations
>altogether (which would be nice in freeing up some CPU cycles during that
>time) and simply duplicate or even triplicate the dataset so on read-back I
>would be able to restore valid data if one of 3 sets does not match.  Also if
>I save in triplicate, it would be quite fast using the page-write mode, but
>is there any advantage to saving the repeated datasets in different pages?
>Data integrity is key here, but if it costs me some CPU cycles, that's fine.
>
>Any ideas on what's better?  Perhaps something other that these 2 options?
>
>Cheers,
>-Neil.

Hi, Neil:-

I often triplicate critical data, but I like to separate it into different
pages, and avoid certain locations. You do have to allow for 3 write cycles,
which is quite a few msec worst case with Fowler-Nordheim tunneling NV memory,
not a problem at all if you use FRAM (but it's single-sourced and more
expensive). I also attempt to repair bad data.

It depends a bit on what you are worried about as a cause of data corruption,
of course-- whether it's EEPROM failure or some external influence.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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