11.5.5 CMU_HFXOCTRL - HFXO Control Register
Offset
Bit Position
0x024
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reset
0
0
0
0x0
0
0
0
0x0
0
Access
R
W
R
W
R
W
R
W
R
W
R
W
R
W
R
W
R
W
Name
Bit
Name
Reset
Access Description
31
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
30
AUTOSTARTRDY-
SELRAC
0
RW
Automatically Start HFXO on RAC Wake-up and Select It Upon
HFXO Ready
This bit enables automatic HFXO start-up and HFXO selection when ready on RAC wake-up. Allowed to change at any
time.
29
AUTOSTARTSE-
LEM0EM1
0
RW
Automatically Start and Select of HFXO Upon EM0/EM1 Entry
From EM2/EM3
This bit enables automatic start-up and immediate selection of the HFXO when in EM0/EM1 (also after entry from EM2/
EM3). Note that setting this bit to 1 will stall HFSRCCLK until HFXO becomes ready. Allowed to change at any time.
28
AUTOSTAR-
TEM0EM1
0
RW
Automatically Start of HFXO Upon EM0/EM1 Entry From EM2/EM3
This bit enables automatic start-up of the HFXO when in EM0/EM1 (also after entry from EM2/EM3) without causing an
automatic HFXO selection. Allowed to change at any time.
27
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
26:24
LFTIMEOUT
0x0
RW
HFXO Low Frequency Timeout
Configures the start-up delay for HFXO measured in LFECLK cycles. Only change when both HFXO and LFECLK are off.
Value
Mode
Description
0
0CYCLES
Timeout period of 0 cycles (disabled)
1
2CYCLES
Timeout period of 2 cycles
2
4CYCLES
Timeout period of 4 cycles
3
16CYCLES
Timeout period of 16 cycles
4
32CYCLES
Timeout period of 32 cycles
5
64CYCLES
Timeout period of 64 cycles
6
1KCYCLES
Timeout period of 1024 cycles
7
4KCYCLES
Timeout period of 4096 cycles
Reference Manual
CMU - Clock Management Unit
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