Re: 2GB MMC/SD cards

[Pierre Ossman]

Pierre Ossman wrote:
> Pierre Ossman wrote:
>> Matt Reimer wrote:
>>> I suspect that a lot of these readers are broken, assuming 512 byte
>>> blocks.
>>>
>> That's what I thought until I looked closer at the Sandisk specs. Until
>> we can see what the official specs say, we won't really know what the
>> correct behaviour is. The Nokia boys working on the 770 have a copy.
>> Perhaps someone here knows how to get in touch with one of them that can
>> have a look?
>>
> 
> With the help of Khasim Syed, who happens to have access to the MMC
> spec, we now know what's in the spec. Unfortunately, what's in there is
> the same text that's in Russell's card specs, which state that only
> WRITE_BL_LEN is supported.
> 

New information. Version 4.2 of the MMC spec changes the wording to this:

* WRITE_BL_LEN
Block length for write operations. See READ_BL_LEN for field coding.
Note that the support for 512B write access is mandatory for all cards.

Similar wording for READ_BL_LEN, but that isn't of interest to us.

Rgds
Pierre

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