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SD Card ECC Errors

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tristan:
Does anyone here have much experience with the use of MicroSD cards in industrial applications? We have designed and currently manufacture a product used on electric vehicles which uses a MicroSD card for data storage. Everything seemed to be working fine but we appear to have a problem with data corruption on the memory cards.

We have recently added software to check the card for errors at power up if an unclean shutdown is detected. This simply attempts to read each block of data from the card in turn.  We are seeing large numbers of ECC errors (read data error token 0x04). When we do see them we overwrite the block in question with zeros which I would expect to clear the error which it does in some cases. However after doing this other blocks on the card will report ECC errors and we never seem to be able to clear them all.

Does anyone have any experience of this or ideas of what could be causing large numbers of ECC errors? The problems do not occur on the bench but they do on the vehicle which points to some kind of noise or EMC related problem but information on this type of problem seems thin on the ground.

Thanks

Tristan

Psi:
i don't really have experience with this but i do remember from the Openmoko neo1973 mailing list that sd/microsd cards are very picky about timing and it varies quite a bit between brands.

Cheap sd/microsd cards often don't meet the official timing specs.
So if i was you i'd first try a good quality sandisk card and see if that gives any problems.

If you get errors with a sandisk card then it's a pretty good sign that there's a timing problem in your code that talks to the card.

IanB:
Also check your power supply. I believe SD cards need a very clean and very stable power supply (3.3 V I think). On a vehicle you might be experiencing some power supply glitches.

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