Altera cyclone V Technical Reference page 975

cv_5v4
2016.10.28
terminate if the host issues an SD/SDIO STOP or STOP_TRANSMISSION (CMD12) command before all
the data bytes are received from the card.
Single-block Data Read
If the
ctype
respectively, and CRC-16 is separately generated and checked for 1, 4, or 8 data lines, respectively. If there
is a CRC-16 mismatch, the data path signals a data CRC error to the BIU. If the received end bit is not 1,
the BIU receives an End-bit Error (EBE).
Multiple-block Data Read
If the
transfer_mode
value of the
machine receives data in blocks, where the number of bytes in a block is equal to the block size, including
the internally-generated CRC-16.
If the
ctype
respectively, and CRC-16 is separately generated and checked for 1, 4, or 8 data lines, respectively. After a
data block is received, if the remaining byte count becomes zero, the data path signals a data transfer to the
†
BIU.
If the remaining data bytes are greater than zero, the data path state machine causes another data block to
be received. If CRC-16 of a received data block does not match the internally-generated CRC-16, a data
CRC error to the BIU and data reception continue further data transmission until all bytes are
transmitted. Additionally, if the end of a received data block is not 1, data on the data path signals
terminate the bit error to the CIU and the data-receive state machine terminates data reception, waits for
data timeout, and signals to the BIU that the data transfer is complete.
If the
send_auto_stop
generated when the last data block is transferred, where no extra bytes are transferred from the card. The
end bit of the STOP command might not exactly match the end bit of the last data block.
If the requested block size for data transfers to cards is less than 4, 16, or 32 bytes for 1-bit, 4-bit, or 8-bit
data transfer modes, respectively, the data-transmit state machine terminates the data transfer when all
data is transferred, at which point the internally-generated STOP command is loaded in the command
path. Data received from the card after that are then ignored by the data path.
If the
bytcnt
transfer. For this type of data transfer, the data-receive state machine continues the block-read data
transfer until the host software issues an SD/SDIO STOP or STOP_TRANSMISSION (CMD12)
command.
Auto-Stop
The controller internally generates an SD/SDIO STOP command and is loaded in the command path
when the
send_auto_stop
exact number of data bytes using a stream read or write for the MMC, and a multiple-block read or write
for SD memory transfer for SD cards. The software must set the
following details:
The following list describes conditions for the AUTO_STOP command:
SD/MMC Controller
Send Feedback
register is set to a 1-bit, 4-bit, or 8-bit data transfer, data is received from 1, 4, or 8 data lines,
bit in the
cmd
register, the transfer is a multiple-block read-data transfer. The data-receive state
block_size
†
register is set to a 1-bit, 4-bit, or 8-bit data transfer, data is received from 1, 4, or 8 data lines,
bit in the
cmd
register is 0 (the block size must be greater than zero), the transfer is an open-ended block
†
bit in the
†
†
†
register is clear and the value of the
register is set to 1, the SD/SDIO STOP command is internally
register is set to 1. The AUTO_STOP command helps to send an
cmd
Single-block Data Read
register is not equal to the
bytcnt
†
†
†
bit according to the
send_auto_stop
†
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