Sdio Argument Register (Sdio_Arg) - ST STM32F102 Series Reference Manual

SDIO interface (SDIO)
Bit 9 PWRSAV: Power saving configuration bit.
For power saving, the SDIO_CK clock output can be disabled when the bus is idle by setting
PWRSAV:
0: SDIO_CK clock is always enabled.
1: SDIO_CK is only enabled when the bus is active.
Bit 8 CLKEN: Clock enable bit
0: SDIO_CK is disabled.
1: SDIO_CK is enabled.
Bits 7:0 CLKDIV: Clock divide factor.
This field defines the divide factor between the input clock (SDIOCLK) and the output clock
(SDIO_CK): SDIO_CK frequency = SDIOCLK / [CLKDIV + 2].
Note: 1 While the SD/SDIO card or MultiMediaCard is in identification mode, the SDIO_CK
frequency must be less than 400 kHz.
2 The clock frequency can be changed to the maximum card bus frequency when relative
card addresses are assigned to all cards.
3 After a data write, data cannot be written to this register for seven HCLK clock periods.
SDIO_CK can also be stopped during the read wait interval for SD I/O cards: in this case the
SDIO_CLKCR register does not control SDIO_CK.
19.9.3

SDIO Argument Register (SDIO_ARG)

Address offset: 0x08
Reset value: 0x0000 0000
The SDIO_ARG register contains a 32-bit command argument, which is sent to a card as
part of a command message.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
Bits 31:0 CMDARG: Command argument.
Command argument sent to a card as part of a command message. If a command contains
an argument, it must be loaded into this register before writing a command to the command
register.
454/690
CMDARG
r/w
9 8 7 6 5 4 3
RM0008
2 1 0