Lpc2000

Rob Jansen wrote:

>Tom,
>
>  
>
>>I'm getting really confused here.  AFAIK: MMC cards you can purchase 
>>don't have the encyrpto capabilities.   While Secure Digital card can 
>>have encrypted data, but also can behave as an MMC protocol card.  While 
>>I also understand that pure MMC cards do exist, they are becomming very 
>>very hard to find???
>>
>>Here comes the confusion on my part: If I have a Secure Digital / MMC 
>>card that is working with my system, but I don't have the encryption 
>>information to do the security mode: isn't this, in fact, an MMC Card?
>> 
>>
>>    
>>
>
>I can only tell you if you sign your life away ...
>
>SD originated from MMC on top of MMC it contains 4 bit mode and encryption.
>To distinguish between SD and MMC there are some differences; the SD 
>card is thicker than MMC (so you can never put an SD card in a pure MMC 
>slot) and the initialization is different.
>As far as I know they both share the same SPI mode commands, but I have 
>to get this from the specs since I only used the real MMC/SD modes on 
>LPC3000 and other ARM variants.
>All basic commands for reading and writing from the card are the same 
>and result in the same responses. SD has extra commands for security and 
>SDIO and MMC has some extra commands for a streaming mode.
>
>Originated from the same source, MMC and SD are changing into different 
>directions.
>MMC is now also coming with more bits (up to 8 bits) and a higher clock 
>frequency (52 MHz).
>
>  
>
Thank you, since working with these cards for the first time, I was 
getting confused.  A lot of people seem to be calling the 4bit interface 
"SD" and the SPI interface "MMC".  AFAIK, the only real difference, the 
thickness aside, is that one does encryption and the other doesn't.

I was beginning to become concerned that if I continued to refer to MMC 
that others wouldn't know that you can plug an SD card into the software 
and have it runs just fine.  Maybe I'll just drop the term altogether 
then, after all, I am using SD cards + an SD socket.

Regards

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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