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AT32F435/437
Series Reference Manual
2022.11.11
Page 572
Rev 2.03
1: Enabled
Bit 0
TFREN
0x0
rw
Data transfer enabled bit
This bit is set or cleared by software. If this bit is set, data
transfer starts. The DCSM enters the Wait_S or Wait_R
state, depending on the direction bit TFRDIR. The DCSM
goes to the read wait state if the RDWTSTART bit is set
from the beginning of the transfer. It is not necessary to
clear the enable bit after the end of data transfer but the
SDIO_DTCTRL must be updated to enable a new data
transfer.
0: Disabled
1: Enabled
Note: This register cannot be written within seven HCLK clo ck periods after data is written.
25.4.10 SDIO data counter register (SDIO_DTCNTR)
The SDIO_DTCNTR register loads the value from the SDIO_DTLEN register when the DCSM moves
from the idle state to the Wait_R or Wait_S state. During the data transfer, the counter value decrements
to 0, and then the DCSM enters the idle state and sets the data status end flag bit DTCMPL.
Bit
Register
Reset value
Type
Description
Bit 31: 25 Reserved
0x00
resd
Kept at its default value.
Bit 24: 0
CNT
0x0000000
ro
Data count value
When this register is read, the number of data bytes to be
transferred is returned. Write access has no effect.
Note: This register can be read only when the data transfer is complete.
25.4.11 SDIO status register (SDIO_STS)
The SDIO_STS is a read-only register, containing two types of flags:
Static flags (bits [23: 22, 10: 0]): These bits can be cleared by writing to the SDIO_INTCLR
register.
Dynamic flags (bit [21: 11]): These bit status changes with the state of the corresponding logic
(for example, BUT full or empty flag is set or cleared as data written to the BUF)
Bit
Register
Reset value
Type
Description
Bit 31: 23 Reserved
0x000
resd
Kept at its default value.
Bit 22
IOIF
0x0
ro
SD I/O interrupt received
Bit 21
RXBUF
0x0
ro
Data available in receive BUF
Bit 20
TXBUF
0x0
ro
Data available in transmit BUF
Bit 19
RXBUFE
0x0
ro
Receive BUF empty
Bit 18
TXBUFE
0x0
ro
Transmit BUF empty
If hardware flow control is enabled, the TXBUF_E signal
becomes valid when the BUF contains two words.
Bit 17
RXBUFF
0x0
ro
Receive BUF full
If hardware flow control is enabled, the RXBUF_F
becomes valid two words before the BUF is full.
Bit 16
TXBUFF
0x0
ro
Transmit BUF full
Bit 15
RXBUFH
0x0
ro
Receive BUF half full
There are at least 8 words in the BUF. This flag bit can be
used as DMA request.
Bit 14
TXBUFH
0x0
ro
Transmit BUF half empty:
At least 8 words can be written to the BUF. This flag bit can
be used as DMA request.
Bit 13
DORX
0x0
ro
Data receive in progress
Bit 12
DOTX
0x0
ro
Data transmit in progress
Bit 11
DOCMD
0x0
ro
Command transfer in progress
Bit 10
DTBLKCMPL
0x0
ro
Data block sent/received CRC check passed)
Bit 9
SBITERR
0x0
ro
Start bit not detected on all data signals in wide bus mode
Bit 8
DTCMPL
0x0
ro
Data end (data counter, SDIO CNT, is zero)
Bit 7
CMDCMPL
0x0
ro
Command sent (no response required)
Bit 6
CMDRSPCMPL
0x0
ro
Command response (CRC check passed)
Bit 5
RXERRO
0x0
ro
Received BUF overrun error