GD32W51x User Manual
808
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Bits
Fields
Descriptions
31
DIV[8]
MSB of Clock division
This field defines the MSB division betw een the input clock (SDIOCLK) and the
output clock, refer to bit 7:0 of SDIO_CLKCTL
30:15
Reserved
Must be kept at reset value.
14
HWCLKEN
Hardw are Clock Control enable bit
If this bit is set, hardw are controls the SDIO_CK on/off depending on the system
bus is very busy or not. There is no underrun/overrun error w hen this bit is set,
because hardw are can close the SDIO_CK w hen almost underrun/overrun.
0: HW Clock control is disabled
1: HW Clock control is enabled
13
CLKEDGE
SDIO_CK clock edge selection bit
0: Select the rising edge of the SDIOCLK to generate SDIO_CK
1: Select the falling edge of the SDIOCLK to generate SDIO_CK
12:11
BUSMODE[1:0]
SDIO card bus mode control bit
00: 1-bit SDIO card bus mode selected
01: 4-bit SDIO card bus mode selected
10: 8-bit SDIO card bus mode selected
10
CLKBYP
Clock bypass enable bit
This bit defines the SDIO_CK is directly SDIOCLK or not.
0: NO bypass, the SDIO_CK refers to DIV bits in SDIO_CLKCTL register.
1: Clock bypass, the SDIO_CK is directly from SDIOCLK (SDIOCLK/1).
9
CLKPWRSAV
SDIO_CK clock dynamic sw itch on/off for pow er saving.
This bit controls SDIO_CK clock dynamic sw itch on/off w hen the bus is idle for
pow er saving
0: SDIO_CK clock is alw ays on
1: SDIO_CK closed w hen bus idle
8
CLKEN
SDIO_CK clock output enable bit
0: SDIO_CK is disabled
1: SDIO_CK is enabled
7:0
DIV[7:0]
Clock division
This field and DIV[8] bit defines the division factor to generator SDIO_CK clock to
card. The SDIO_CK is divider from SDIOCLK if CLKBYP bit is 0, and the SDIO_CK
frequency = SDIOCLK / (DIV[8:0] + 2).
Note:
Betw een Tw o w rite accesses to this register, it needs at least 3 SDIOCLK + 2 pclk2 w hich used
to sync the registers to SDIOCLK clock domain.