C8051F980-C-GM Datasheet, PDF (167/325 Pages) Silicon Laboratories – Ultra Low Power, 8-2 kB Flash, Capacitive Sensing MCU

C8051F99x-C8051F98x
15.7. 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 wak-
ing 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 PMU0CF and PMU0FL 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 PMU0CF and PMU0FL must be cleared before the
device can enter suspend or sleep mode. After clearing the wake-up flags, each of the enabled wake-up
events should be checked in the individual peripherals to ensure that a wake-up event did not occur while
the wake-up flags were being cleared.
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