7.6.2 Determining the Event that Caused the Last Wakeup
When waking from Idle mode, the CPU will vector to the interrupt which caused it to wake up. When waking from Stop mode, the
RSTSRC register may be read to determine the cause of the last reset.
Upon exit from Suspend or Sleep mode, the wake-up flags in the power management registers can be read to determine the event
which caused the device to wake up. After waking up, the wake-up flags will continue to be updated if any of the wake-up events occur.
Wake-up flags are always updated, even if they are not enabled as wake-up sources.
All wake-up flags enabled as wake-up sources in the power management registers must be cleared before the device can enter Sus-
pend or Sleep mode. After clearing the wake-up flags, each of the enabled wake-up events should be checked in the individual periph-
erals to ensure that a wake-up event did not occur while the wake-up flags were being cleared.
7.7 Power Management Control Registers
7.7.1 PCON0: Power Control 0
Bit
7
6
5
4
3
2
1
0
Name
GF5
GF4
GF3
GF2
GF1
GF0
STOP
IDLE
Access
RW
RW
RW
RW
RW
RW
RW
RW
Reset
0
0
0
0
0
0
0
0
SFR Page = ALL; SFR Address: 0x87
Bit
Name
Reset
Access
Description
7
GF5
0
RW
General Purpose Flag 5.
This flag is a general purpose flag for use under firmware control.
6
GF4
0
RW
General Purpose Flag 4.
This flag is a general purpose flag for use under firmware control.
5
GF3
0
RW
General Purpose Flag 3.
This flag is a general purpose flag for use under firmware control.
4
GF2
0
RW
General Purpose Flag 2.
This flag is a general purpose flag for use under firmware control.
3
GF1
0
RW
General Purpose Flag 1.
This flag is a general purpose flag for use under firmware control.
2
GF0
0
RW
General Purpose Flag 0.
This flag is a general purpose flag for use under firmware control.
1
STOP
0
RW
Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
0
IDLE
0
RW
Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
To ensure the MCU enters a low power state upon entry into Idle or Stop mode, the one-shot circuit should be enabled by clearing the
BYPASS bit in the FLSCL register.
EFM8SB2 Reference Manual
Power Management and Internal Regulators
silabs.com
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