
Rev. 1.00
93 of 486
July 31, 2018
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F50231/HT32F50241
6 Clock Control Unit (CKCU)
HSI Control Register – HSICR
This register is to control the frequency trimming of HSI RC oscillation.
Offset:
0x040
Reset value:
0xXXXX_0000 where X is undefined
31
30
29
28
27
26
25
24
Reserved
HSICOARSE
Type/Reset
RO X RO X RO X RO X RO X
23
22
21
20
19
18
17
16
HSIFINE
Type/Reset RW X RW X RW X RW X RW X
RW X
RW X
RW X
15
14
13
12
11
10
9
8
Reserved
Type/Reset
7
6
5
4
3
2
1
0
FLOCK
REFCLKSEL
TMSEL
ATMSEL
LTRSEL
ATCEN
TRIMEN
Type/Reset RO 0 RW 0 RW 0 RW 0 RW 0 RW 0 RW 0 RW 0
Bits
Field
Descriptions
[28:24]
HSICOARSE HSI Clock Coarse Trimming Value
These bits are initialized automatically at startup. They are adjusted by factory
trimming and cannot trim by program.
[23:16]
HSIFINE
HSI Clock Fine Trimming Value
These bits are initialized automatically at startup. They are also adjusted by factory
trimming. But these bits provide an additional user-programmable trimming value
that is added to the HSICOARSE[4:0] bits to get more accurate or compensate
the variations in voltage and temperature that influence the frequency of the HSI.
It can be programmed by software or automatically adjusted by the Auto Trimming
Controller (ATC) with an external reference clock.
[7]
FLOCK
Frequency Lock
0: HSI frequency is not trimmed into target range
1: HSI frequency is trimmed into target range
[6:5]
REFCLKSEL Reference Clock Selection
0x: Select 32.768 kHz external low speed clock source (LSE)
1x: Select external pin (CKIN) 1 kHz pulse
These bits are used to select the reference clock for the HSI Auto Trimming Controller.
[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[7:0] bits in the HSI Control 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 selected the automatic trimming method by ATC hardware for HSI RC oscillator.
[2]
LTRSEL
Lock Target Range Selection
0: 0.1 % variation
1: 0.2 % variation
This bit is selected the lock target range of the internal HSI RC oscillator trimming
function for 0.1 % or 0.2 % variation.