SDIO
Commands Table
| CMD Index | Type | Argument | Response | Abbreviation | Command Description |
|---|---|---|---|---|---|
| CMD12 | ac | [31:0] stuff bits | R1b | STOP_TRANSMISSION | Forces the card to stop transmission. |
| 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. |
Responses
R1 (normal response command)
R1 is a 48-bit response.
Linux flags:
- MMC_RSP_CRC
| 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.
| 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
| SD Specifications Part E1 SDIO Simplified Specification | http://academy.cba.mit.edu/classes/networking_communications/SD/SD.pdf |