AT83SND2CMP3 datasheet(51/97 Pages) ATMEL

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AT83SND2CMP3

7524B–MP3–05/06

MultiMedia Card

Controller

The AT83SND2CMP3 implements a MultiMedia Card (MMC) controller. The MMC is

used to store MP3 encoded audio files in removable Flash memory cards that can be

easily plugged or removed from the application.

Card Concept

The basic MultiMedia Card concept is based on transferring data via a minimum number

of signals.

Card Signals

The communication signals are:

•

CLK: with each cycle of this signal a one bit transfer on the command and data lines

is done. The frequency may vary from zero to the maximum clock frequency.

•

CMD: is a bi-directional command channel used for card initialization and data

transfer commands. The CMD signal has 2 operation modes: open-drain for

initialization mode and push-pull for fast command transfer. Commands are sent

from the MultiMedia Card bus master to the card and responses from the cards to

the host.

•

DAT: is a bi-directional data channel. The DAT signal operates in push-pull mode.

Only one card or the host is driving this signal at a time.

Card Registers

Within the card interface five registers are defined: OCR, CID, CSD, RCA and DSR.

These can be accessed only by the corresponding commands.

The 32-bit Operation Conditions Register (OCR) stores the V

DD voltage profile of the

card. The register is optional and can be read only.

The 128-bit wide CID register carries the card identification information (Card ID) used

during the card identification procedure.

The 128-bit wide Card-Specific Data register (CSD) provides information on how to

access the card contents. The CSD defines the data format, error correction type, maxi-

mum data access time, data transfer speed, and whether the DSR register can be used.

The 16-bit Relative Card Address register (RCA) carries the card address assigned by

the host during the card identification. This address is used for the addressed host-card

communication after the card identification procedure.

The 16-bit Driver Stage Register (DSR) can be optionally used to improve the bus per-

formance for extended operating conditions (depending on parameters like bus length,

transfer rate or number of cards).

Bus Concept

The MultiMedia Card bus is designed to connect either solid-state mass-storage mem-

ory or I/O-devices in a card format to multimedia applications. The bus implementation

allows the coverage of application fields from low-cost systems to systems with a fast

data transfer rate. It is a single master bus with a variable number of slaves. The Multi-

Media Card bus master is the bus controller and each slave is either a single mass

storage card (with possibly different technologies such as ROM, OTP, Flash etc.) or an

I/O-card with its own controlling unit (on card) to perform the data transfer.

The MultiMedia Card bus also includes power connections to supply the cards.

The bus communication uses a special protocol (MultiMedia Card bus protocol) which is

applicable for all devices. Therefore, the payload data transfer between the host and the

cards can be bi-directional.

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