MMC or SD Memory in SPI mode

[Dave Schabel]

Does anyone here know if I can use an SD and/or MMC memory in SPI mode (in
an embedded application) such that the card can be read through a standard
computer SD/MMC reader?

Thanks,
Dave

 

[Scott Miller]

Whether the card can be read through a standard computer reader or not has
nothing to do with the access mode you're using - it's all about the file
format.

But yes, I'm doing that now. I've got a 128 MB SD card hooked up to the SPI
port of an AT91SAM7S64, and it can find and read files. Writing and
deleting are still in the works, but I got the basic block-write command
implemented.

You probably want FAT16 format. There are others that computers will read,
but that's pretty much the standard for these flash devices.

Scott

 

[Dave Schabel]

Great, that's what I thought the answer would be.
Are there any standard app notes on doing this? I know that FAT16 is
documented in lots of places, but I was just wondering if there was some
sample source code or something that you've found.

Thanks again, Scott!

 

[Scott Miller]

I think Circuit Cellar just ran an article on FAT and SD/MMC. Could have
used that myself about a year ago. Not sure if it's online or not, but it
presented a nice introduction.

Scott