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SDIO clock control register (SDIO_CLKCTRL)
Offset address: 0x04
Reset value: 0x0000 0000
SDIO_CLKCTRL register controls SDIO_CLK to output the clock.
Field
Name
R/W
Description
7:0
CLKDIV
R/W
Clock Divide Factor
This domain defines the division factor between input clock (SDIOCLK)
and output clock (SDIO_CLK):
SDIO_CLK frequency=SDIOCLK/[ 2].
8
CLKEN
R/W
Clock Enable
0: Disable
1: Enable
9
PWRSAV
R/W
Power Saving Mode Configuration
Reduce power consumption by disabling SDIO_ CLK outputs beyond
the bus activity.
0: Enable
1: Disable
10
BYPASSEN R/W
Clock Divider Bypass Enable
Before driving SDIO_CLK to output signals, it is required to divide the
frequency of SDIOCLK; however, if the divider is bypassed, SDIOCLK
will directly drive SDIO_CLK to output signals.
0: Disable
1: Enable
12:11
WBSEL
R/W
Wide Bus Mode Select
Select bus mode for different bits, corresponding to different SDIO_D
bits.
00: Default, using SDIO_D0
01: 4 bits, using SDIO_D[3:0]
10: 8 bits, using SDIO_D[7:0]
11: Reserved
13
DEPSEL
R/W
SDIO_CLK Dephasing Select
Select SDIOCLK rising edge or falling edge to generate SDIO_CLK.
0: Rising edge
1: Falling edge
14
HFCEN
R/W
HW Flow Control Enable
0: Disable
1: Enable
31:15
Reserved
Note:
(1) When SD/SD I/O card or multimedia card is in identification mode, the frequency of
SDIO_CLK must be less than 400kHz.
(2) When all cards have been assigned the corresponding address, the clock frequency can be
changed to the maximum frequency allowed by the card bus.