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12.6.3.3
Waking from sleep modes
There are two types of wake-up sources from sleep mode, synchronous and asynchronous.
Synchronous wake-up sources are all non-masked interrupts. Asynchronous wake-up sources
are AST, WDT, external interrupts from EIC, external reset, external wake pin (WAKE_N), and
all asynchronous wake-ups enabled in the Asynchronous Wake Up Enable (AWEN) register. The
In Shutdown the only wake-up sources are external reset, external wake-up pin or AST. See
Notes:
1. The sleep mode index is used as argument for the sleep instruction.
2. Only PB modules operational, as HSB module clocks are stopped.
3. WDT only available if clocked from pre-enabled OSC32K.
12.6.3.4
SleepWalking
In all sleep modes where the PBx clocks are stopped, except for Shutdown mode, the device
can partially wake up if a PBx module asynchronously discovers that it needs its clock. Only the
requested clocks and clock sources needed will be started, all other clocks will remain masked
to zero. E.g. if the main clock source is OSC0, only OSC0 will be started even if other clock
sources were enabled in normal mode. Generic clocks can also be started in a similar way. The
state where only requested clocks are running is referred to as SleepWalking.
The time spent to start the requested clock is mostly limited by the startup time of the given clock
source. This allows PBx modules to handle incoming requests, while still keeping the power con-
sumption at a minimum.
When the device is SleepWalking any asynchronous wake-up can wake the device up at any
time without stopping the requested PBx clock.
All requests to start clocks can be masked by writing to the Peripheral Power Control Register
(PPCR), all requests are enabled at reset.
During SleepWalking the interrupt controller clock will be running. If an interrupt is pending when
entering SleepWalking, it will wake the whole device up.
12.6.3.5
Precautions when entering sleep mode
Modules communicating with external circuits should normally be disabled before entering a
sleep mode that will stop the module operation. This will prevent erratic behavior caused by
entering or exiting sleep modes. Please refer to the relevant module documentation for recom-
mended actions.
Table 12-3.
Wake-up Sources
Sleep Mode
Wake-up Sources
0
Idle
Synchronous, Asynchronous
1
Frozen
2
Standby
Asynchronous
3
Stop
Asynchronous
4
DeepStop
Asynchronous
5
Static
6
Shutdown
External reset, External wake-up pin