
Rev. 1.00
110 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
6 Clock Control Unit (CKCU)
Bits
Field
Descriptions
[4]
TMSEL
Trimming Mode Selection
0: Automatic by Auto Trimming Controller
1: Manual by user program
This bit is used to select the HSI RC oscillator trimming function by ATC hardware
or user programming via the HSIFINE field in this register.
[3]
ATMSEL
Automatic Trimming Mode Selection
0: Auto Trimming Controller is used binary search to approach the target range
1: Auto Trimming Controller is used linear search to approach the target range
This bit is used to select the automatic trimming method by ATC hardware for the
HSI RC oscillator.
[2]
LTRSEL
Lock Target Range Selection
0: 0.1 % variation
1: 0.2 % variation
This bit is used to select the lock target range of the internal HSI RC oscillator
trimming function for 0.1 % or 0.2 % variation.
[1]
ATCEN
ATC Enable
0: Disable Auto Trimming Controller
1: Enable Auto Trimming Controller
[0]
TRIMEN
Trimming Enable
0: HSI Trimming is disabled
1: HSI Trimming is enabled
Setting this bit high enables the HSI RC oscillator trimming function by ATC
hardware or user programming.
HSI Auto Trimming Counter Register – HSIATCR
This register contains the counter value of the HSI auto trimming controller
Offset:
0x044
Reset value: 0x0000_0000
31
30
29
28
27
26
25
24
Reserved
Type/Reset
23
22
21
20
19
18
17
16
Reserved
Type/Reset
15
14
13
12
11
10
9
8
Reserved
ATCNT
Type/Reset
RO 0 RO 0 RO 0 RO 0 RO 0 RO 0
7
6
5
4
3
2
1
0
ATCNT
Type/Reset RO 0 RO 0 RO 0 RO 0 RO 0 RO 0 RO 0 RO 0
Bits
Field
Descriptions
[13:0]
ATCNT
Auto Trimming Counter
This bit field contains the counter value of the HSI auto trimming controller.