MultiMediaCard (MMC)

5.1.4Pull-up and Pull-down

Table 5-4and Table 5-5show the pull-up and pull-down resistors required for SDCard and MMC devices according to their respective specifications.

Table 5-4. SDCard Pull-up and Pull-down Resistors

Signal

Pull-up or Pull-down

Min

Max

Remark

 

 

 

 

 

CMD

pull-up

10k

100k

Prevents bus floating

 

 

 

 

 

DAT0-DAT3

pull-up

10k

100k

Prevents bus floating

 

 

 

 

 

WP1

pull-up

Any value sufficient to prevent bus floating

NOTE: 1. This resistor is shown in the specification but the value is not specified

Table 5-5. MMC Pull-up and Pull-down Resistors

Signal

Pull-up or Pull-down

Min

Max

Remark

 

 

 

 

 

CMD

pull-up

4.7k

100k

Prevents bus floating

 

 

 

 

 

DAT

pull-up

50k

100k

Prevents bus floating

 

 

 

 

 

5.2Utilized Features

The applications processor MultiMediaCard controller has these features:

Data transfer rates as fast as 20 Mbps

A16 bit response FIFO

Dual receive data FIFOs

Dual transmit FIFOs

Support for two MMCs in either MMC or SPI mode

The sample schematics in this section support MMC and SDCard and are configured to use MMC or SPI mode.

The applications processor MultiMediaCard controller and the MMC device have the same maximum data rate, 20 Mbps, so their communication rates are compatible. However, because the maximum applications processor MultiMediaCard controller data rate is 20 Mbps and the maximum SDCard data rate is 25 Mbps, SDCard devices are not utilized to their fullest extent.

The circuit designs presented in this guide (Figure 5-1and Figure 5-2) only show support for one SDCard or MMC device, but the applications processor MultiMediaCard controller handles as many as two devices.

5-6

PXA250 and PXA210 Applications Processors Design Guide

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Image 62
Intel PXA250 and PXA210 Utilized Features, SDCard Pull-up and Pull-down Resistors, MMC Pull-up and Pull-down Resistors

PXA250 and PXA210 specifications

The Intel PXA250 and PXA210 processors, part of the Intel XScale architecture, were introduced in the early 2000s, targeting mobile and embedded applications. They are known for their low power consumption, high performance, and advanced multimedia capabilities, making them suitable for a wide range of devices, including PDAs, smartphones, and other portable computing devices.

The PXA250, which operates at clock speeds ranging from 400 MHz to 624 MHz, features a superscalar architecture that allows it to issue multiple instructions per clock cycle. This enhances the overall performance for demanding applications while maintaining low power usage. It supports a variety of peripheral interfaces, including USB, Ethernet, and various memory types, which contributes to its versatility in different product designs.

One of the key technologies in the PXA250 is the integrated Intel Smart Repeat Technology, which optimizes data processing, thereby reducing the amount of power consumed during operation. This feature is particularly important for battery-powered devices, as it extends the overall battery life, allowing for longer usage times in mobile environments. Additionally, the PXA250 includes a dedicated graphics acceleration unit, which enables enhanced graphics and multimedia performance suited to modern applications at the time.

In contrast, the PXA210 is a more entry-level processor, aimed at cost-sensitive applications. Operating at lower clock speeds, typically around 200 MHz to 400 MHz, it forgoes some of the advanced performance features of the PXA250 while still offering a good balance of performance and power efficiency. The PXA210 is less complex, making it suitable for simpler devices that do not require the extensive capabilities of the PXA250.

Both processors utilize the Intel XScale architecture, which is based on the ARM instruction set. They are built on a 0.13-micron process technology, enabling higher density and lower power consumption compared to their predecessors. With integrated memory controllers and bus interfaces, they facilitate efficient data handling and connectivity options.

In summary, both the Intel PXA250 and PXA210 processors played a crucial role in the evolution of mobile computing by providing powerful processing capabilities with energy efficiency. Their features and technologies enabled device manufacturers to create innovative products that catered to the growing demand for portable devices during that era.