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Intel PXA250 and PXA210 Applications Processors

Intel PXA250 and PXA210 Applications Processors

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MultiMediaCard (MMC)<br />

5.1.4 Pull-up <strong>and</strong> Pull-down<br />

Table 5-4 <strong>and</strong> Table 5-5 show the pull-up <strong>and</strong> pull-down resistors required for SDCard <strong>and</strong> MMC<br />

devices according to their respective specifications.<br />

Table 5-4. SDCard Pull-up <strong>and</strong> Pull-down Resistors<br />

Signal Pull-up or Pull-down Min Max Remark<br />

CMD pull-up 10kΩ 100kΩ Prevents bus floating<br />

DAT0-DAT3 pull-up 10kΩ 100kΩ Prevents bus floating<br />

WP 1 pull-up — — Any value sufficient to prevent bus floating<br />

NOTE: 1. This resistor is shown in the specification but the value is not specified<br />

Table 5-5. MMC Pull-up <strong>and</strong> Pull-down Resistors<br />

Signal Pull-up or Pull-down Min Max Remark<br />

CMD pull-up 4.7kΩ 100kΩ Prevents bus floating<br />

DAT pull-up 50kΩ 100kΩ Prevents bus floating<br />

5.2 Utilized Features<br />

The applications processor MultiMediaCard controller has these features:<br />

• Data transfer rates as fast as 20 Mbps<br />

• A16 bit response FIFO<br />

• Dual receive data FIFOs<br />

• Dual transmit FIFOs<br />

• Support for two MMCs in either MMC or SPI mode<br />

The sample schematics in this section support MMC <strong>and</strong> SDCard <strong>and</strong> are configured to use MMC<br />

or SPI mode.<br />

The applications processor MultiMediaCard controller <strong>and</strong> the MMC device have the same<br />

maximum data rate, 20 Mbps, so their communication rates are compatible. However, because the<br />

maximum applications processor MultiMediaCard controller data rate is 20 Mbps <strong>and</strong> the<br />

maximum SDCard data rate is 25 Mbps, SDCard devices are not utilized to their fullest extent.<br />

The circuit designs presented in this guide (Figure 5-1 <strong>and</strong> Figure 5-2) only show support for one<br />

SDCard or MMC device, but the applications processor MultiMediaCard controller h<strong>and</strong>les as<br />

many as two devices.<br />

5-6 <strong>PXA250</strong> <strong>and</strong> <strong>PXA210</strong> <strong>Applications</strong> <strong>Processors</strong> Design Guide

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