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M0A21/M0A23 Series
May 06, 2022
Page
144
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
HIRC Trim Control Register (SYS_HIRCTRIMCTL)
Register
Offset
R/W
Description
Reset Value
SYS_HIRCTRIMCTL
0xF0
R/W
HIRC Trim Control Register
0x0008_0000
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
BOUNDARY
15
14
13
12
11
10
9
8
Reserved
REFCKSEL
BOUNDEN
CESTOPEN
7
6
5
4
3
2
1
0
RETRYCNT
LOOPSEL
Reserved
FREQSEL
Bits
Description
[31:21]
Reserved
Reserved.
[20:16]
BOUNDARY
Boundary Selection
Fill the boundary range from 0x1 to 0x1F, 0x0 is reserved.
Note:
This field is effective only when the BOUNDEN(
SYS_HIRCTRIMCTL[9]) is enable.
[15:11]
Reserved
Reserved.
[10]
REFCKSEL
Reference Clock Selection
0 = HIRC trim reference clock is from LXT (32.768 kHz).
1 = Reserved.
Note:
If there is no reference clock (LXT) when the rc_trim is enabled,
CLKERIF (SYS_HIRCTRIMCTL[2])
will be set to 1.
[9]
BOUNDEN
Boundary Enable Bit
0 = Boundary function Disabled.
1 = Boundary function Enabled.
[8]
CESTOPEN
Clock Error Stop Enable Bit
0 = The trim operation is keep going if clock is inaccuracy.
1 = The trim operation is stopped if clock is inaccuracy.
[7:6]
RETRYCNT
Trim Value Update Limitation Count
This field defines that how many times the auto trim circuit will try to update the HIRC trim value before the
frequency of HIRC locked.
Once the HIRC locked, the internal trim value update counter will be reset.
If the trim value update counter reached this limitation value and frequency of HIRC still doesn’t lock, the
auto trim operation will be disabled and FREQSEL will be cleared to 00.
00 = Trim retry count limitation is 64 loops.
01 = Trim retry count limitation is 128 loops.
10 = Trim retry count limitation is 256 loops.
11 = Trim retry count limitation is 512 loops.
[5:4]
LOOPSEL
Trim Calculation Loop Selection