MMC/SD Module Overview
Setup and Use of the Multimedia Card/Secure Digital Host Controller Application Note, Rev. 0
2
Freescale Semiconductor
2
MMC/SD Module Overview
This section provides an overview of both the Multimedia Card (MMC) and Secure Digital Card (SD)
modules. The MMC/SD module includes the following features:
•
Supports up to 10 cards (including one SD card)
•
Password protection for cards
•
Built-in programmable frequency counter for MMC/SD bus
•
Maskable hardware interrupt for card detection (insertion/removal), SD I/O interrupt, internal
status, and FIFO status
•
Contains an integrated 32
×
16-bit FIFO
•
Supports plug-and-play (Pop)
•
Supports many SD functions including multiple I/O and combined I/O and memory
•
Supports up to seven I/O functions plus one memory on a single SD I/O card
•
Card can interrupt MMC/SD module
•
Support single or multiple block access, or stream access to the card for read, write, or erase
operations
•
Supports SD I/O ReadWait and interrupt detection during 1- or 4-bit access
2.1
Multimedia Card (MMC) Protocol
The MMC is low cost data storage and communication medium implemented as a hardware card with a
simple control unit and a compact, easy-to-implement interface that is designed to cover a wide variety of
applications. It is based on an advanced 7-pin serial bus designed to operate over a voltage range of 2.0 to
3.6 V. Note that the maximum operating voltage range for the i.MX is 3.3 V. Therefore the i.MX-based
design is limited to a supply range of 2.0 to 3.3 V.
2.2
Secure Digital Card (SD) Protocol
The SD is an extended version of the MMC with two additional pins. The additional pins are designed to
meet the security, capacity, performance, and environmental requirements inherent in new audio and
video consumer electronic devices. The physical form factor and data transfer protocol are compatible
with the MMC. The SD is composed of a memory card and an I/O card.
3
MMC/SD Module Configuration
The MMC card has 7 pins and the SD card has 9 pins. The pins are used to communicate with other
functions within the card. The pin assignment and form factor are shown in
Table 1
.