View source for SDIO

=== Commands Table ===
{| class="wikitable"
|+
!CMD Index
!Type
!Argument
!Response
!Abbreviation
!Command Description
|-
|CMD0
|bc
|[31:0] stuff bits
|
|GO_IDLE_STATE
|Resets all cards to idle state.
|-
|CMD2
|bcr
|[31:0] stuff bits
|R2
|ALL_SEND_CID
|Asks any card to send the CID num-bers on the CMD line (any card that is connected to the host will respond).
|-
|CMD6
|
|
|
|
|
|-
|CMD7
|ac
|
|R1b
(only from the selected card)
|SELECT/DESELECT_CARD
|
|-
|CMD8
|bcr
|[31:12] reserved bits
[11:8] supply voltage(VHS)

[7:0] check pattern
|R7
|SEND_IF_COND
|Sends SD Memory Card interface condition, which includes host supply voltage information and asks the card whether card supports voltage. Reserved bitsshall be set to '0'.
|-
|CMD9
|ac
|[31:16] RCA
[15:0] stuff bits
|R2
|SEND_CSD
|Addressed card sends its card-specific data (CSD) on the CMD line.
|-
|CMD12
|ac
|[31:0] stuff bits
|R1b
|STOP_TRANSMISSION
|Forces the card to stop transmission.
|-
|CMD13
|ac
|[31:16] RCA
[15]  Send  Task Status Register

[14:0] stuff bits
|R1
|SEND_STATUS/SEND_TASK_STATUS
|CQ not enabled:[15] = ‘0’ or ‘1’, Addressed card sends its status register.

CQ enabled: [15]=’0’, Addressed card sends its status register. [15]=’1’, Addressed card sends task statusregister.
|-
|CMD16
|ac
|[31:0] block length
|R1
|SET_BLOCKLEN
|In the case of a Standard Capacity SD Memory Card, this command sets the block length (in bytes) for all following block commands (read, write, lock). Default block length is fixed to 512Bytes. Set length is valid for memory access commands only if partial block read operation are allowed in CSD. 
|-
|CMD17
|adtc
|[31:0] data address
|R1
|READ_SINGLE_BLOCK
|In the case of a Standard Capacity SD Memory Card, this command, this command reads a block of the size selected by the SET_BLOCKLEN command.
In case of SDHC and SDXC Cards, block length is fixed 512Bytes regardless of the SET_BLOCKLEN command.
|-
|CMD18
|adtc
|[31:0] data address
|R1
|READ_MULTIPLE_BLOCK
|Continuously  transfers  data  blocks from card to host until interrupted by a STOP_TRANSMISSION command.
|-
|CMD25
|adtc
|[31:0] data address
|R1
|WRITE_MULTIPLE_BLOCK
|Continuously writes blocks of data until a STOP_TRANSMISSION follows. Block  length  is  specified  the  same  as WRITE_BLOCK command.
|-
|CMD41
|
|
|
|
|
|-
|CMD55
|
|
|
|
|
|}

=== Responses ===

==== R1 (normal response command) ====
R1 is a 48-bit response.

Linux flags:
* MMC_RSP_CRC
{| class="wikitable"
!Bit position
!47
!46
![45:40]
![39:8]
![7:1]
!0
|-
|Width (bits)
|1
|1
|6
|32
|7
|1
|-
|Value
|'0'
|'0'
|x
|x
|x
|'1'
|-
|Description
|start bit
|transmission bit
|command index
|card status
|CRC7
|end bit
|}

==== R1b ====
R1b is a 48-bit response.

==== R2 (CID, CSD register) ====
R2 is a 136-bit response.

Linux flags:
* MMC_RSP_136

==== R3 (OCR register) ====
R3 is a 48-bit response.
{| class="wikitable"
!Bit position
!47
!46
![45:40]
![39:8]
![7:1]
!0
|-
|Width (bits)
|1
|1
|6
|32
|7
|1
|-
|Value
|'0'
|'0'
|'111111'
|x
|'1111111'
|'1'
|-
|Description
|start bit
|transmission bit
|reserved
|OCR register
|reserved
|end bit
|}

==== R6 (Published RCA response) ====
R6 is a 48-bit response.

==== R7 (Card interface condition) ====
R7 is a 48-bit response.

== References ==
{| class="wikitable"
!
!
|-
|SD Specifications Part E1 SDIO Simplified Specification
|http://academy.cba.mit.edu/classes/networking_communications/SD/SD.pdf
|}