Sdio Data Counter Register (Sdio_Dcount) - STMicroelectronics STM32F405 Reference Manual

RM0090
Bit 2 DTMODE: Data transfer mode selection 1: Stream or SDIO multibyte data transfer.
Bit 1 DTDIR: Data transfer direction selection
Bit 0 DTEN: Data transfer enabled bit
Note: After a data write, data cannot be written to this register for three SDIOCLK (48 MHz) clock
periods plus two PCLK2 clock periods.
The meaning of the DTMODE bit changes according to the value of the SDIOEN bit. When
SDIOEN=0 and DTMODE=1, the MultiMediaCard stream mode is enabled, and when
SDIOEN=1 and DTMODE=1, the peripheral enables an SDIO multibyte transfer.
31.9.10

SDIO data counter register (SDIO_DCOUNT)

Address offset: 0x30
Reset value: 0x0000 0000
The SDIO_DCOUNT register loads the value from the data length register (see
SDIO_DLEN) when the DPSM moves from the Idle state to the Wait_R or Wait_S state. As
data is transferred, the counter decrements the value until it reaches 0. The DPSM then
moves to the Idle state and the data status end flag, DATAEND, is set.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
Reserved
Bits 31:25 Reserved, must be kept at reset value
Bits 24:0 DATACOUNT: Data count value
Note: This register should be read only when the data transfer is complete.
0: Block data transfer
1: Stream or SDIO multibyte data transfer
0: From controller to card.
1: From card to controller.
Data transfer starts if 1b is written to the DTEN bit. Depending on the direction bit, DTDIR,
the DPSM moves to the Wait_S, Wait_R state or Readwait if RW Start is set immediately at
the beginning of the transfer. It is not necessary to clear the enable bit after the end of a data
transfer but the SDIO_DCTRL must be updated to enable a new data transfer
r r r r r r
When this bit is read, the number of remaining data bytes to be transferred is returned. Write
has no effect.
DocID018909 Rev 11
Secure digital input/output interface (SDIO)
DATACOUNT
r r r r r r r
9 8 7 6 5
r r r r r r r
4 3 2 1 0
r r r r r
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