Application-Specific And General Commands; Command Types; Command Formats - Motorola DragonBall MC9328MX1 Reference Manual

20.7.8.1 Application-Specific and General Commands

The MMC/SD module system is designed to provide a standard interface for a variety of applications
types. In this environment, there is a need for specific customers/applications features. To implement these
features, two types of generic commands are defined in the standard: application-specific commands
(ACMD) and general commands (GEN_CMD).
When the card receives the
application-specific command. ACMDs have the same structure as regular MMC commands and can have
the same CMD number. The card recognizes it as ACMD because it appears after
When the command immediately following the
command, the standard command is used.
For example, when the card has a definition for
immediately following
APP_CMD
the card receives CMD7 immediately following
definition for ACMD7, this is interpreted as the standard
To use one of the manufacturer specific ACMDs the MMC/SD module must perform the following steps:
1. Send (CMD55).
APP_CMD
— The card responds to the MMC/SD module, indicating that the APP_CMD bit is set and an
ACMD is now expected.
2. Send the required ACMD.
— The card responds to the MMC/SD module, indicating that the APP_CMD bit is set and that the
accepted command is interpreted as an ACMD. When a non-ACMD is sent it is handled by the
card as a normal MMC command and the APP_CMD bit in the Card Status Register stays clear.
When an invalid command is sent (neither ACMD nor CMD) it is handled as a standard MMC illegal
command error.
The bus transaction for a GEN_CMD is the same as the single block read or write commands
( , CMD24 or
WRITE_BLOCK
direction of the data transfer rather than the address and the data block has vendor-specific format and
meaning.
The card must be selected (in transfer state) before sending
defined by
SET_BLOCKLEN

20.7.8.2 Command Types

Both application-specific and general commands are divided into the following four types:
Broadcast command (BC)—Sent to all cards; no responses returned.
•
Broadcast Command with Response (BCR)—Sent to all cards; responses received from all cards
•
simultaneously.
Addressed (Point-to-Point) Command (AC)—Sent to the card that is selected; does not include
•
a data transfer on the SD_DAT line(s).
Addressed (Point-to-Point) Data Transfer Command (ADTC)—Sent to the card that is selected;
•
includes data transfer on the SD_DAT line(s).

20.7.8.3 Command Formats

All commands are sent over the SD_CMD line, are a fixed length of 48 bits, and are in the format shown in
Table 20-24.
MOTOROLA Multimedia Card/Secure Digital Host Controller Module (MMC/SD)
(CMD55) command, the card expects the next command to be an
APP_CMD
APP_CMD
SD_STATUS
(CMD55), this is interpreted as
APP_CMD
READ_SINGLE_BLOCK,
(CMD16). The response to
Functional Example for the MMC/SD Module
(CMD55) is not a defined application-specific
(ACMD13), and receives CMD13
SD_STATUS
(CMD55) and the card does not have a
(SELECT/DESELECT_CARD)
CMD17). In this case, the argument denotes the
(CMD56). The data block size is
GEN_CMD
(CMD56) is in R1b format.
GEN_CMD
(CMD55).
APP_CMD
(ACMD13). However, when
CMD7.
20-55