From: Randy McLaughlin <>
Date: Wed Feb 2 19:25:41 2005

From: "Eric Smith" <>
Sent: Wednesday, February 02, 2005 6:48 PM
> jpero wrote:
>> What kind of protocol that MMC talks in serial fashion?
> MMC protocol, which is a synchronous serial protocol. At the
> electrical and timing level it is similar to SPI and Microwire, but
> the command set and such are AFAICT not derived from anything else.
> If I'm not mistaken, a PDF file of the MMC specification used to be
> publicly available at
> but I can't find it there now. :-(
> Apparently they have now added 4-bit and 8-bit wide interface modes
> and higher clock rates (up to 52 MHz) to the latest version of the
> standard, probably in response to the SD card specification which
> allows 4-bit wide 25 MHz operation. However, it appears to me that
> SD has almost completely displaced MMC in the market, so I'm a bit
> skeptical that these new MMC modes are going to wind up in many
> products.
> Eric

Here are the pages I used:

Received on Wed Feb 02 2005 - 19:25:41 GMT

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