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Intel PXA250 and PXA210 Applications Processors

Intel PXA250 and PXA210 Applications Processors

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MultiMediaCard (MMC) 5<br />

The MultiMediaCard (MMC) is a low cost data storage <strong>and</strong> communication media. The MMC<br />

supports the translation protocol from a st<strong>and</strong>ard MMC or Serial Peripheral Interface (SPI) bus to<br />

an application bus.<br />

The MMC controller in the applications processor is compliant with The MultiMediaCard System<br />

Specification, Version 2.1. The only exception is one <strong>and</strong> three byte data transfers are not<br />

supported. The MMC controller is capable of communicating with a card in MMC or SPI mode.<br />

Your application is responsible for specifying the MMC controller communication mode.<br />

5.1 Schematics<br />

The MultiMediaCard (MMC) controller on the applications processor supports MMC <strong>and</strong> SDCard<br />

devices. (The MMC controller does not support SDCard nibble mode.) This section presents<br />

several options on how to connect each type of device to the controller.<br />

5.1.1 Signal Description<br />

MMC controller signal functions are described in Table 5-1.<br />

Table 5-1. MMC Signal Description<br />

Signal Name Input/Output Description<br />

MMCLK Output Clock signal to MMC<br />

MMCMD BiDirectional Comm<strong>and</strong> line<br />

MMDAT BiDirectional Data line<br />

MMCCS0 Output Chip Select 0<br />

MMCCS1 Output Chip Select 1<br />

The MMCLK, MMCCS0, <strong>and</strong> MMCCS1 signals are routed through alternate functions within the<br />

applications processor general purpose input/output (GPIO) module. Each of these signals can be<br />

programmed to a particular GPIO pin.<br />

The signals defined in The MultiMediaCard System Specification for an MMC device are CLK,<br />

CMD, <strong>and</strong> DAT which correspond to the MMCLK, MMCMD, <strong>and</strong> MMDAT in the applications<br />

processor, respectively. The two chip selects in the controller are for the MMC SPI mode <strong>and</strong><br />

correspond to the reserved pin of two different devices, defined in the specification.<br />

The signals defined in the Physical Layer Specification of the SD Memory Card Specifications for<br />

an SDCard device are CLK, CMD, <strong>and</strong> DAT0-DAT3. The obvious difference is the number of<br />

DAT signals. In addition, the socket for an SDCard contains mechanical switches for write protect<br />

(WP) <strong>and</strong> card detect (CD). For an SDCard to be connected to the MMC controller, only one data<br />

line, DAT0, is used. Otherwise the signal mapping remains the same as an MMC device. The WP<br />

<strong>and</strong> CD switches on the socket are discussed in Section 5.1.2, “How to Wire” on page 5-2.<br />

<strong>PXA250</strong> <strong>and</strong> <strong>PXA210</strong> <strong>Applications</strong> <strong>Processors</strong> Design Guide 5-1

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