MultiMediaCard (MMC)

5

The MultiMediaCard (MMC) is a low cost data storage and communication media. The MMC supports the translation protocol from a standard MMC or Serial Peripheral Interface (SPI) bus to an application bus.

The MMC controller in the applications processor is compliant with The MultiMediaCard System Specification, Version 2.1. The only exception is one and three byte data transfers are not supported. The MMC controller is capable of communicating with a card in MMC or SPI mode. Your application is responsible for specifying the MMC controller communication mode.

5.1Schematics

The MultiMediaCard (MMC) controller on the applications processor supports MMC and SDCard devices. (The MMC controller does not support SDCard nibble mode.) This section presents several options on how to connect each type of device to the controller.

5.1.1Signal Description

MMC controller signal functions are described in Table 5-1.

Table 5-1. MMC Signal Description

Signal Name

Input/Output

Description

 

 

 

MMCLK

Output

Clock signal to MMC

 

 

 

MMCMD

BiDirectional

Command line

 

 

 

MMDAT

BiDirectional

Data line

 

 

 

MMCCS0

Output

Chip Select 0

 

 

 

MMCCS1

Output

Chip Select 1

 

 

 

The MMCLK, MMCCS0, and MMCCS1 signals are routed through alternate functions within the applications processor general purpose input/output (GPIO) module. Each of these signals can be programmed to a particular GPIO pin.

The signals defined in The MultiMediaCard System Specification for an MMC device are CLK, CMD, and DAT which correspond to the MMCLK, MMCMD, and MMDAT in the applications processor, respectively. The two chip selects in the controller are for the MMC SPI mode and correspond to the reserved pin of two different devices, defined in the specification.

The signals defined in the Physical Layer Specification of the SD Memory Card Specifications for an SDCard device are CLK, CMD, and DAT0-DAT3. The obvious difference is the number of DAT signals. In addition, the socket for an SDCard contains mechanical switches for write protect (WP) and card detect (CD). For an SDCard to be connected to the MMC controller, only one data line, DAT0, is used. Otherwise the signal mapping remains the same as an MMC device. The WP and CD switches on the socket are discussed in Section 5.1.2, “How to Wire” on page 5-2.

PXA250 and PXA210 Applications Processors Design Guide

5-1

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Intel PXA250 and PXA210 MultiMediaCard MMC, Schematics, MMC Signal Description, Signal Name Input/Output Description

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.