at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 371

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

MultiMedia Card Interface (MCI)
Overview
1790A–ATARM–11/03
The MultiMedia Card Interface (MCI) supports the MultiMediaCard (MMC) Specification V2.2
and the SD Memory Card Specification V1.0.
The MCI includes a command register, response registers, data registers, timeout counters
and error detection logic that automatically handle the transmission of commands and, when
required, the reception of the associated responses and data with limited processor overhead.
The MCI supports stream, block and multi-block data read and write, and is compatible with
the Peripheral Data Controller channels, minimizing processor intervention for large buffer
transfers.
The MCI operates at a rate of up to Master Clock divided by 2 and supports interfacing of up to
16 slots (depending on the product). Each slot may be used to interface with a MultiMediaCard
bus (up to 30 Cards) or with an SD Memory Card. Only one slot can be selected at a time
(slots are multiplexed). A bit in the Command Register performs this selection.
The SD Memory Card communication is based on a 9-pin interface (clock, command, four
data and three power lines) and the MultiMediaCard on a 7-pin interface (clock, command,
one data and three power lines).
The SD Memory Card interface also supports MultiMedia Card operations. The main differ-
ences between SD and MultiMedia Cards are the initialization process and the bus topology.
The main features of the MCI are:
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Compatibility with MultiMedia Card Specification Version 2.2
Compatibility with SD Memory Card Specification Version 1.0
Cards clock rate up to Master Clock divided by 2
Embedded power management to slow down clock rate when not used
Supports up to sixteen multiplexed slots (product-dependent)
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Support for stream, block and multi-block data read and write
Supports connection to Peripheral Data Controller
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One slot for one MultiMediaCard bus (up to 30 cards) or one SD Memory Card
Minimizes processor intervention for large buffer transfers
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