9.5.6 EMU_EM4CTRL - EM4 Control Register
Offset
Bit Position
0x018
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
0x0
0x0
0
0
0
0
Access
W1
R
W
R
W
R
W
R
W
R
W
Name
Bit
Name
Reset
Access Description
31:18
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
17:16
EM4ENTRY
0x0
W1
Energy Mode 4 Entry
This register is used to enter the Energy Mode 4 sequence. Writing the sequence 2,3,2,3,2,3,2,3,2 will enter the part into
Energy Mode 4.
15:6
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
5:4
EM4IORETMODE
0x0
RW
EM4 IO Retention Disable
Determine when IO retention will be applied and removed.
Value
Mode
Description
0
DISABLE
No Retention: Pads enter reset state when entering EM4
1
EM4EXIT
Retention through EM4: Pads enter reset state when exiting EM4
2
SWUNLATCH
Retention through EM4 and Wakeup: software writes UNLATCH regis-
ter to remove retention
3
RETAINULFRCO
0
RW
ULFRCO Retain during EM4S
Retain the ULFRCO upon EM4S entry. If set to 1, an already running ULFRCO will be retained in its running state in EM4.
ULFRCO will always be retained if EM4STATE is in EM4H.
2
RETAINLFXO
0
RW
LFXO Retain during EM4
Retain the LFXO upon EM4(SH/H) entry. If set to 1, an already running LFXO will be retained in its running state in EM4.
1
RETAINLFRCO
0
RW
LFRCO Retain during EM4
Retain the LFRCO upon EM4(S/H) entry. If set to 1, an already running LFRCO will be retained in its running state in EM4.
0
EM4STATE
0
RW
Energy Mode 4 State
When set, the system will enter Hibernate state (EM4H) when entering EM4. In EM4H, the regulator will be on in reduced
mode allowing for RTCC. Otherwise, when entering in EM4, the regulator will be disabled allowing for lowest power mode,
Shutoff state (EM4S).
Value
Mode
Description
0
EM4S
EM4S Shutoff state
1
EM4H
EM4H Hibernate state
EFM32JG1 Reference Manual
EMU - Energy Management Unit
silabs.com
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