ST STM32L4+ Series Reference Manual page 1980

Secure digital input/output MultiMediaCard interface (SDMMC)
Note: DTEN shall not be used to start data transfer with SD, SDIO and e•MMC cards.
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Wait_Ack state: the data path waits for the boot acknowledgment token.
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Wait_R state: the data path, if the data counter is not zero and data is not hold, waits
for a start bit on SDMMC_D[n:0]. If the data counter is zero or data is hold, wait for the
FIFO to be empty.
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1980/2301
The DPSM moves to the Wait_R state if it receives an error free acknowledgment
before a timeout.
When a pattern different from the acknowledgment is received an
acknowledgment status error is generated, and the Ack fail status flag (ACKFAIL)
is set. The DPSM stays in Wait_Ack.
If it reaches a timeout (ACKTIME) before it detects a start bit, it sets the timeout
status flag (ACKTIMEOUT). The DPSM stays in Wait_Ack.
When the CPSM Abort signal is set it moves to the Idle state and sets the
DABORT flag.
In block mode, if a start bit is received before a timeout the DPSM moves to the
Receive state and loads the data block counter with DBLOCKSIZE.
In SDIO multibyte mode, if a start bit is received before a timeout the DPSM
moves to the Receive state and loads the data block counter with DATALENGTH.
In stream mode, if a start bit is received before a timeout the DPSM moves to the
Receive state and loads the data counter with DATALENGTH.
if the data counter (DATACOUNT) equals zero (end of data) the DPSM moves to
the Idle state when the receive FIFO is empty and the DATAEND flag is set.
If it reaches a timeout (DATATIME) before it detects a start bit, it sets the timeout
status flag (DTIMEOUT) and the DPSM stays in the WAIT_R state.
If the CPSM Abort signal is set:
If DATACOUNT > 0, the DPSM moves to the Idle state when the FIFO is empty
and when IDMAEN = 0 reset with FIFORST, and sets the DABORT flag.
If DATACOUNT is zero normal operation is continued, there will be no DABORT
flag since the transfer has completed normally.
if the DTHOLD bit is set:
- When DATACOUNT > 0, the DPSM moves to the Idle state when the receive
FIFO is empty and when IDMAEN = 0 reset with FIFORST, and issues the DHOLD
flag. When Holding the timeout is disabled. When an CPSM Abort signal is
received during Holding, the transfer is Aborted.
RM0432 Rev 6
RM0432