At 09:13 AM 1/22/04 -1000, you wrote:
>>The one doc I recall as being the most useful was R2_MMC1.pdf
>>and was originated by SanDisk.  I seem to remember lots of
>
>Does anyone have the sd spec? (How do sd commands differ from mmc?)
>
>Jay

It's been a while but as I remember, SD cards can be operated as either SD
or MMC.  I looked up enough of the specs to make a few slight mods to the
MMC code such that I can also read/write SD cards as well.  I think to
actually work in SD mode requires proprietary ($$$) security info. I didn't
need the secure mode so didn't bother with it.

One other slight difference is that the SD format has two extra lines
(total of 9 vs 7). It's setup to transfer in nibble mode - 4 lines parallel
rather than one line serial so it has the option of faster transfers. You
can buy sockets with 9 pins and the MMC card will fit it so your device can
be made to operate with either type of card.

Tom

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