Altera Cyclone V Device Handbook page 721

cv_54011
2013.12.30
Parameter
check_response_crc
cmd_index
Related Information
Auto-Stop
Refer to this table for information about setting the send_auto_stop parameter.
Stream Read and Write
In a stream transfer, if the byte count is equal to 0, the software must also send the SD/SDIO STOP command.
If the byte count is not 0, when a given number of bytes completes a transfer, the controller sends the STOP
command automatically. Completion of this AUTO_STOP command is reflected by the Auto_command_done
interrupt. A response to an AUTO_STOP command is written to the resp1 register. A stream transfer is
allowed only for card interfaces with a 1-bit data bus.
A stream read requires the same steps as the block read described in Single-Block or Multiple-Block Read,
except for the following bits in the cmd register:
• transfer_mode = 0x1 (for stream transfer)
• cmd_index = 20 (SD/SDIO CMD20)
A stream write requires the same steps as the block write mentioned in Single-Block or Multiple-Block Write,
except for the following bits in the cmd register:
• transfer_mode = 0x1 (for stream transfer)
• cmd_index = 11 (SD/SDIO CMD11)
Related Information
• Single-Block or Multiple-Block Read
Refer to this section for more information about a stream read.
• Single-Block or Multiple-Block Write
Refer to this section for more information about a stream write.
Packed Commands
To reduce overhead, read and write commands can be packed in groups of commands either all read or
all write that transfer the data for all commands in the group in one transfer on the bus. Use the SD/SDIO
SET_BLOCK_COUNT (CMD23) command to state ahead of time how many blocks will be transferred.
Then issue a single READ_MULTIPLE_BLOCK or WRITE_MULTIPLE_BLOCK command to read or write
multiple blocks.
• SET_BLOCK_COUNT set block count (number of blocks transferred using the
READ_MULTIPLE_BLOCK or WRITE_MULTIPLE_BLOCK command)
• READ_MULTIPLE_BLOCK multiple-block read command
• WRITE_MULTIPLE_BLOCK multiple-block write command
Packed commands are organized in packets by the application software and are transparent to the controller.
SD/MMC Controller
Send Feedback
Value
Command
Index
on page 11-22
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1 0 Controller must not check response CRC
1 Controller must check response CRC
Set this parameter to the command number. For example,
set to 24 for SD/SDIO WRITE_BLOCK (CMD24) or 25
for WRITE_MULTIPLE_BLOCK (CMD25).
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on page 11-38
on page 11-41
Stream Read and Write
Comment
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11-43
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