
Rev. 1.00
90 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
6 Clock Control Unit (CKCU)
Register Descriptions
Global Clock Configuration Register – GCFGR
This register specifies the clock source for PLL/CKOUT.
Offset:
0x000
Reset value: 0x0000_0302
31
30
29
28
27
26
25
24
LPMOD
Reserved
Type/Reset WC 0 WC 0 RO 0
23
22
21
20
19
18
17
16
Reserved
Type/Reset
15
14
13
12
11
10
9
8
CKREFPRE
Reserved
PLLSRC
Type/Reset RW 0 RW 0 RW 0 RW 0 RW 0
RW 1
7
6
5
4
3
2
1
0
Reserved
CKOUTSRC
Type/Reset
RW 0 RW 1 RW 0
Bits
Field
Descriptions
[31:29]
LPMOD
Lower Power Mode Status
000: When chip is in running mode
001: When chip once entered Sleep mode
010: When chip once entered Deep-Sleep1 mode
011: When chip once entered Deep-Sleep2 mode
Others: Reserved
Set by hardware. Reset by software writing b11x.
[15:11]
CKREFPRE
CK_REF Clock Prescaler Selection
CK_REF = CK_PLL / (CK 1) / 2
00000: CK_REF = CK_PLL / 2
00001: CK_REF = CK_PLL / 4
...
11111: CK_REF = CK_PLL / 64
Set and reset by software to control the CK_REF clock prescaler setting.
[8]
PLLSRC
PLL Clock Source Selection
0: External 4 ~ 16 MHz crystal oscillator clock is selected (HSE)
1: Internal 8 MHz RC oscillator clock is selected (HSI)
Set and reset by software to control the PLL clock source.
[2:0]
CKOUTSRC CKOUT Clock Source Selection
000: CK_REF is selected, CK_REF = CK_PLL / (CK 1) / 2
001: (HCLKC / 16) is selected
010: (CK_SYS / 16) is selected
011: (CK_HSE / 16) is selected
100: (CK_HSI / 16) is selected
101: CK_LSE is selected
110: CK_LSI is selected
111: Reserved
Set and reset by software to control the CKOUT clock source.