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Registers
Table 18. MMC Command Register (MMCCMD) Field Descriptions (continued)
Bit | Field | Value Description |
12 | STRMTP | Stream enable. |
0If WDATX = 1, the data transfer is a block transfer. The data transfer stops after the movement of the programmed number of bytes (defined by the programmed block size and the programmed number of blocks).
1If WDATX = 1, the data transfer is a stream transfer. Once the data transfer is started, the data transfer does not stop until the MMC controller issues a stop command to the memory card.
11 | DTRW |
| Write enable. |
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| 0 | If WDATX = 1, the data transfer is a read operation. |
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| 1 | If WDATX = 1, the data transfer is a write operation. |
RSPFMT | Response format (expected type of response to the command). | ||
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| 0 | No response. |
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| 1h | R1, R4, R5, or R6 response. 48 bits with CRC. |
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| 2h | R2 response. 136 bits with CRC. |
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| 3h | R3 response. 48 bits with no CRC. |
8 | BSYEXP |
| Busy expected. If an R1b (R1 with busy) response is expected, set RSPFMT = 1h and BSYEXP = 1. |
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| 0 | A busy signal is not expected. |
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| 1 | A busy signal is expected. |
7 | PPLEN |
| Push pull enable. |
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| 0 | Push pull driver of CMD line is disabled (open drain). |
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| 1 | Push pull driver of CMD line is enabled. |
6 | Reserved | 0 | Reserved. |
CMD | Command index. This field contains the command index for the command to be sent to the memory | ||
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| card. |
Figure 31. Command Format
47 | 46 | 45 | 40 | 39 |
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| 24 |
Start | Transmission |
| Command index |
| Argument, high part |
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23 |
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| 8 | 7 | 1 | 0 |
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| Argument, low part |
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| CRC7 |
| End |
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| Table 19. Command Format |
Bit Position of |
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Command | Register | Description |
47 | - | Start bit |
46 | - | Transmission bit |
Command index (CMD) | ||
MMCARGHL | Argument, high part (ARGH) | |
MMCARGHL | Argument, low part (ARGL) | |
- | CRC7 | |
0 | - | End bit |
SPRUE30B | Multimedia Card (MMC)/Secure Digital (SD) Card Controller | 53 |
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