The MultiMediaCard (MMC) Controller on the Intel? PXA250 Applications Processor can
communicate with either:
? A MultiMediaCard (MMC)
? A Secure Digital (SD) Memory Card
? A Secure Digital I/O (SDIO) card
Since the MMC controller was originally intended to support MMC cards only, this application
note describes how to use the SD Memory Card and SDIO card and some of the pitfalls in doing so.
This application note gives a detailed description of the following:
? The difference between MMC, SD Memory Cards, and SDIO cards
? How to connect the SD Memory Card or SDIO card to the PXA250 applications processor
? How to reset, initialize, and communicate with the SD Memory Card or SDIO card in MMC
and SPI mode
? Describe performance issues of using the SD Memory Card and SDIO card with the MMC
Controller
This application note assumes that the reader has a general knowledge of MMC, SD Memory
Cards, SDIO cards, and the PXA250 applications processor. If more information is required, refer
to the respective specification documents; The MultiMediaCard System Specification, SD
Memory Card Specifications, SDIO Card Specification and the Intel? PXA250 and PXA210
Applications Processors Developer’s Manual. In addition, this application note applies to both the
PXA250 applications processor and the PXA210 applications processor, however, for brevity, only
the PXA250 applications processor is mentioned in the text.
All of the connections and code for the SD Memory Card and SDIO card are based on the
respective specifications. The information for the SD Memory Card has been verified on the
Lubbock evaluation platform. The information on SDIO is presented from a theoretical perspective based on the specification.