9.3.1 Energy Modes
EFM32 Jade Gecko features six main energy modes, referred to as Energy Mode 0 (EM0 Active) through Energy Mode 4 (EM4 Shut-
off). The Cortex-M3 is only available for program execution in EM0 Active. In EM0 Active/EM1 Sleep any peripheral function can be
enabled. EM2 DeepSleep through EM4 Shutoff, also referred to as low energy modes, provide a significantly reduced energy consump-
tion while still allowing a rich set of peripheral functionality. The following
shows the possible transitions
between different energy modes.
Table 9.1. Energy Mode Transitions
Current Mode
EM Transition Action
Enter EM0 Ac-
tive
Enter EM1
Sleep
Enter EM2
DeepSleep
EnterEM3
Stop
EnterEM4 Hi-
bernate
Enter EM4
Shutoff
EM0 Active
Sleep (WFI,
WFE)
Deep Sleep
(WFI, WFE)
Deep Sleep
(WFI, WFE)
EM4 Entry
EM4 Entry
EM1 Sleep
IRQ
Peripheral
wake up done
Peripheral
wake up done
EM2 DeepSleep
IRQ
Peripheral
wake up req
EM3 Stop
IRQ
Peripheral
wake up req
EM4 Hibernate
Wake Up
EM4 Shutoff
Wake Up
1
Peripheral wakeup from EM2/3 to EM1 and then automatically back to EM2/3 when done.
The ADC, and LEUART have the ability to temporarily wake up the part from either EM2 DeepSleep or EM3 Stop to EM1 Sleep in order
to transfer data. Once completed, the part is automatically placed back into the EM2 DeepSleep or EM3 Stop mode.
The Core can always request to go to EM1 Sleep with the WFI or WFE command during EM0 Active. The core will be prevented from
entering EM2 DeepSleep, EM3 Stop, EM4 Hibernate, or EM4 Shutoff if Flash is programming or erasing.
An overview of supported energy modes and available functionality is shown in
Table 9.2 Table 2. EMU Energy Mode Overview on
. By default, the system is configured in the lowest configuration within each energy mode. Functionality may be selectively
enabled.
Table 9.2. EMU Energy Mode Overview
EM0 Active
EM1 Sleep
EM2 Deep-
Sleep
EM3 Stop
EM4 Hiber-
nate
EM4 Shutoff
Wakeup time to EM0 Active/EM1 Sleep
-
-
2 µs
2 µs
160 µs
160 µs
Core Active
On
-
-
-
-
-
High frequency clock and peripherals
Available
Available
-
-
-
-
High frequency oscillators
Available
Available
Available
-
-
-
Low frequency clock and peripherals
Available
Available
Available
-
Available
Available
Low frequency oscillators
Available
Available
Available
Available
Available
Available
Ultra low frequency clock and peripherals
Available
Available
Available
Available
Available
Available
Digital logic and system RAM retained
Available
Available
Available
Available
-
-
RTCC RAM Retained
Available
Available
Available
Available
Available
-
EFM32JG1 Reference Manual
EMU - Energy Management Unit
silabs.com
| Smart. Connected. Energy-friendly.
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