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AT32F435/437
Series Reference Manual
2022.11.11
Page 75
Rev 2.03
4.3.3
Clock configuration register (CRM_CFG)
Access: 0 to 2 wait states. 1 or 2 wait states are inserted only when the access occurs during a clock
source switch.
Bit
Name
Reset value
Type
Description
Bit 31:30
CLKOUT2_SEL1 0x0
rw
Clock output2 selection 1
This field is set and cleared by software.
00: System clock (SCLK) selected
01: Secondary clock output selected by the
CLKOUT2_SEL2 bit in the CRM_MISC1 register
10: External oscillator clock (HEXT) selected
11: PLL clock output
Note: This clock out may be cut off during the startup and
switch of CLKOUT2 clock source. While being used as an
output to the CLKOUT2 pin, the system clock output
frequency must be no more than 50 MHz (the maximum
frequency of an IO port)
Bit 29: 27
CLKOUT2DIV1 0x0
rw
Clock output2 division1
0xx: CLKOUT2
100: CLKOUT2/2
101: CLKOUT2/3
110: CLKOUT2/4
111: CLKOUT2/5
Bit 26: 24
USBDIV
0x0
rw
Clock output1 division1
0xx: CLKOUT1
100: CLKOUT1/2
101: CLKOUT1/3
110: CLKOUT1/4
111: CLKOUT1/5
Bit 23
Reserved
0x0
resd
Kept at its default value.
Bit 22: 21
CLKOUT1_SEL 0x0
rw
Clock output1 selection
This field is set and cleared by software.
00: HICK selected
01: LEXT selected
10: HEXT selected
11: PLL selected
Note: This clock out may be cut off during the startup and
switch of CLKOUT1 clock source. While being used as an
output to the CLKOUT1 pin, the system clock output
frequency must not exceed 50 MHz (the maximum
frequency of an IO port)
Bit 20: 16
ERTCDIV
0x00
rw
HEXT division for ERTC clock
This field is set and cleared by software to divide the HEXT
for ERTC clock.
These bits must be configured before selecting the ERTC
clock source.
00000: Forbidden
00001: Forbidden
00010: HEXT/2
00011: HEXT/3
00100: HEXT/4
…
11110: HEXT/30
11111: HEXT/31