RM0402 Rev 6 905/1163
RM0402 Secure digital input/output interface (SDIO)
921
SDIOCLK are frozen, the APB2 interface is still alive. The FIFO can thus be filled or emptied
even if flow control is activated.
To enable HW flow control, the SDIO_CLKCR[14] register bit must be set to 1. After reset
Flow Control is disabled.
27.8 SDIO registers
The device communicates to the system via 32-bit-wide control registers accessible via
APB2.
27.8.1 SDIO power control register (SDIO_POWER)
Address offset: 0x00
Reset value: 0x0000 0000
Note: At least seven PCLK2 clock periods are needed between two write accesses to this register.
Note: After a data write, data cannot be written to this register for three SDIOCLK clock periods
plus two PCLK2 clock periods.
27.8.2 SDIO clock control register (SDIO_CLKCR)
Address offset: 0x04
Reset value: 0x0000 0000
The SDIO_CLKCR register controls the SDIO_CK output clock.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res.
1514131211109876543210
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. PWRCTRL
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Bits 31:2 Reserved, must be kept at reset value.
[1:0] PWRCTRL: Power supply control bits.
These bits are used to define the current functional state of the card clock:
00: Power-off: the clock to card is stopped.
01: Reserved
10: Reserved power-up
11: Power-on: the card is clocked.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res.
1514131211109876543210
Res.
HWFC
_EN
NEGE
DGE
WID
BUS
BYPAS
S
PWRS
AV
CLKEN CLKDIV
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