[En-Nut-Discussion] support for SD-HC cards

[Alain M.]

Hi Rob,

I read something alarming about micro-SD: it is not mandatory to 
implement SPI interface!

from:<http://en.wikipedia.org/wiki/Sd_card>
"except for microSD where SPI is optional"

I assume that in this case it is not easy to implement (except maybe 
Atmel-ARM9260), correct?

Alain

PragmaLab escreveu:
> Hello all,
> 
> I just finished making the modifications in the code to support SD-HC (high
> capacity) cards. The changes needed to support HC-cards are best described
> by:
> 
> 1) new way of initialising the card (new command 'MMCMD_SEND_IF_COND' is
> introduced in a new init-sequence)
> 2) layout of CSD register has changed (no impact, since the code does not
> use it)
> 3) HC-cards use block addressing iso byte-addressing
> 4) HC-cards use fixed timeouts (no impact, not used in the code)
> 
> Regarding 2) I noticed that the code uses the info it finds in the partion
> table to get the total number of sectors and does not read the CSD register
> for that. This way the new layout for CSD in HC-cards has no implications
> for the code.
> 
> Most modifications are made in mmcard.c and mmcard.h. If somebody wants to
> add it to the CVS-head, just let me know. I tested it with 4 GB SD-HC cards.
> 
> Best regards,
> 
> Rob van Lieshout
> 
> ps: Harald, I did not come across any pattent issues when it comes to using
> SD-HC cards. We just use it in SPI-mode.... 
> 
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