SDIO interface (SDIO) RM0008
430/690
If the host sends a stop transmission command after the card transmits the last block of a
multiple block operation with a predefined number of blocks, it is responded to as an illegal
command, since the card is no longer in the data state. If the host uses partial blocks whose
accumulated length is not block-aligned and block misalignment is not allowed, the card
detects a block misalignment error condition at the beginning of the first misaligned block
(ADDRESS_ERROR error bit is set in the status register).
19.4.7 Stream access, stream write and stream read (MultiMediaCard only)
In stream mode, data is transferred in bytes and no CRC is appended at the end of each
block.
Stream write (MultiMediaCard only)
WRITE_DAT_UNTIL_STOP (CMD20) starts the data transfer from the SDIO card host to the
card, beginning at the specified address and continuing until the SDIO card host issues a
stop command. When partial blocks are allowed (CSD parameter WRITE_BL_PARTIAL is
set), the data stream can start and stop at any address within the card address space,
otherwise it can only start and stop at block boundaries. Because the amount of data to be
transferred is not determined in advance, a CRC cannot be used. When the end of the
memory range is reached while sending data and no stop command is sent by the SD card
host, any additional transferred data are discarded.
The maximum clock frequency for a stream write operation is given by the following
equation fields of the card-specific data register:
● Maximumspeed = maximum write frequency
● TRANSPEED = maximum data transfer rate
● writebllen = maximum write data block length
● NSAC = data read access time 2 in CLK cycles
● TAAC = data read access time 1
● R2WFACTOR = write speed factor
If the host attempts to use a higher frequency, the card may not be able to process the data
and stop programming, set the OVERRUN error bit in the status register, and while ignoring
all further data transfer, wait (in the receive data state) for a stop command. The write
operation is also aborted if the host tries to write over a write-protected area. In this case,
however, the card sets the WP_VIOLATION bit.
Stream read (MultiMediaCard only)
READ_DAT_UNTIL_STOP (CMD11) controls a stream-oriented data transfer.
This command instructs the card to send its data, starting at a specified address, until the
SDIO card host sends STOP_TRANSMISSION (CMD12). The stop command has an
execution delay due to the serial command transmission and the data transfer stops after
the end bit of the stop command. When the end of the memory range is reached while
sending data and no stop command is sent by the SDIO card host, any subsequent data
sent are considered undefined.
Maximumspeed MIN TRANSPEED
82
writebllen
×()NSAC–()
TAAC R2WFACTOR×
-------------------------------------------------------------------------(, )=
To Next Page
Loading...
Need help?
General
