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MMC/SD/SDIO Functional Description
24.4.4 Transfer Process
The process of a transfer is dependent on the type of command. It can be with or without a response, with
or without data.
24.4.4.1 Different Types of Commands
Different types of commands are specific to MMC, SD, or SDIO cards. See the Multimedia Card System
Specification, v4.2, the SD Memory Card Specifications, v2.0, the SDIO Card Specification, Part E1,
v1.10, or the SD Card Specification, Part A2, SD Host Controller Standard Specification, v1.00, for more
details.
24.4.4.2 Different Types of Responses
Different types of responses are specific to MMC, SD, or SDIO cards. See the Multimedia Card System
Specification, v4.2, the SD Memory Card Specifications, v2.0, the SDIO Card Specification, Part E1,
v1.10, or the SD Card Specification, Part A2, SD Host Controller Standard Specification, v1.00, for more
details.
shows how the MMC, SD, and SDIO responses are stored in the MMCHS_RSPxx registers.
Table 24-5. MMC, SD, SDIO responses in the MMCHS_RSPxx registers
Kind of Response
Response Field
Response Register
R1, R1b (normal response), R3, R4,
RESP[39:8]
(1)
R5, R5b, R6
R1b (Auto CMD12 response)
RESP[39:8]
(1)
R2
RESP[127:0]
(1)
(1)
RESP refers to the command response format described in the specifications mentioned above.
When the host controller modifies part of the MMCHS_RSPxx registers, it preserves the unmodified bits.
The host controller stores the Auto CMD12 response in the
[31:0] register because the
Host Controller may have a multiple block data DAT line transfer executing concurrently with a command.
This allows the host controller to avoid overwriting the Auto CMD12 response with the command response
stored in
register and vice versa.
24.4.5 Transfer or Command Status and Error Reporting
Flags in the MMC/SD/SDIOi host controller show status of communication with the card:
•
A timeout (of a command, a data, or a response)
•
A CRC
Error conditions generate interrupts. See
and register description for more details.
Table 24-6. CC and TC Values Upon Error Detected
Error hold in the MMCi.
CC
TC
Comments
register
29
BADA
No dependency with CC nor TC
BADA is related to
register accesses. Its
assertion is not dependent of the ongoing transfer.
28
CERR
1
CC is set upon CERR.
22
DEB
1
TC is set upon DEB.
21
DCRC
1
TC is set upon DCRC.
20
DTO
DTO and TC are mutually exclusive
DCRC and DEB cannot occur with DTO.
19
CIE
1
CC is set upon CIE.
18
CEB
1
CC is set upon CEB.
3389
SWPU177N – December 2009 – Revised November 2010
MMC/SD/SDIO Card Interface
Copyright © 2009–2010, Texas Instruments Incorporated