Clock Source Status Register - Ckst - Holtek HT32F52220 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F52220/HT32F52230
Clock Source Status Register – CKST
This register specifies the clock source status.
Offset: 0x034
Reset value: 0x0100_0003
31
Type/Reset
23
Type/Reset
15
Type/Reset
7
Type/Reset
Bits Field Descriptions
[26:24] HSIST Internal High Speed Clock Occupation Status (CK_HSI)
[17:16] HSEST External High Speed Clock Occupation Status (CK_HSE)
[11:8] PLLST PLL Clock Occupation Status
[2:0] CKSWST Clock Switch Status
The fields are status to indicate which clock source is using as system clock currently.
Rev. 1.10
30 29 28
Reserved
22 21 20
Reserved
14 13 12
Reserved
6 5 4
Reserved
xx1: HSI is used by System Clock (CK_SYS) (SW = 0x03)
x1x: HSI is used by PLL
1xx: HSI is used by Clock Monitor
x1: HSE is used by System Clock (CK_SYS) (SW = 0x02)
1x: HSE is used by PLL
xxx1: PLL is used by System Clock (CK_SYS)
xx1x: Reserved
x1xx: Reserved
1xxx: PLL is used by CK_REF
00x: CK_PLL clock out as system clock
010: CK_HSE as system clock
011: CK_HSI as system clock
110: Reserved
111: CK_LSI as system clock
90 of 366
27 26
HSIST
RO 0 RO
19 18
RO
11 10
PLLST
RO 0 RO 0 RO
3 2
CKSWST
RO 0 RO
25 24
0 RO 1
17 16
HSEST
0 RO 0
9 8
0 RO 0
1 0
1 RO 1
November 09, 2018