at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 381

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

SD Card
Operations
1790A–ATARM–11/03
The MultiMedia Card Interface allows processing of SD Memory Card (Secure Digital Memory
Card) commands. The SD Memory Card will include a copyright protection mechanism that
complies with the security requirements of the SDMI standard, is faster and applicable to
higher memory capacity.
The physical form factor, pin assignment and data transfer protocol are forward-com-patible
with the MultiMedia Card with some additions.
The SD Memory Card communication is based on a 9-pin interface (Clock, Command,
4 x Data and 3 x Power lines). The communication protocol is defined as a part of this specifi-
cation. The main difference between the SD Memory Card and the MultiMedia Card is the
initialization process.
The SD Card Control Register (MCI_SDCR) allows selection of the card slot and the data bus
width.
The SD Card bus allows dynamic configuration of the number of data lines. After power up, by
default, the SD Memory Card will use only DAT0 for data transfer. After initialization, the host
can change the bus width (number of active data lines).
AT91RM3400
381