12.3.2.1 Sleep Modes
Three different sleep modes can be enabled to reduce power consumption.
- Idle
- The CPU stops executing code, resulting in reduced power consumption.
- Standby
- All high-frequency clocks are stopped apart from any peripheral or clock that
are enabled to run in Standby sleep mode. This is enabled by writing the
corresponding RUNSTDBY bit to ‘
1
’. The power consumption is dependent on the enabled functionality. - Power-Down
- All high-frequency clocks are stopped, resulting in a power consumption lower than the Idle sleep mode.
Note:
- Refer to the Sleep Mode Activity tables for further information.
Refer to the Wake-up Time section for information on how the wake-up time is affected by the different sleep modes.
Clock | Peripheral | Active in Sleep Mode | ||
---|---|---|---|---|
Idle | Standby | Power-Down | ||
CLK_CPU | CPU | - | - | - |
CLK_RTC | RTC | X | X(1,2) | X(2) |
CLK_WDT | WDT | X | X | X |
CLK_BOD(3) | BOD | X | X | X |
(4) | CCL | X | X(1) | - |
CLK_PER | ADCn | X | X(1) | - |
TCAn | ||||
TCBn | ||||
All other peripherals | X | - | - |
Note:
- Set the RUNSTDBY bit of the corresponding peripheral to enter an active state.
- In Standby sleep mode, only the RTC functionality requires the RUNSTDBY to be set to enter an active state. In Power-Down sleep mode, only the PIT functionality is available.
- Sampled mode only.
- The clock domain depends on the clock source selected for CCL.
Clock Source | Active in Sleep Mode | |||
---|---|---|---|---|
Idle | Standby | Power-Down | ||
Main clock source | X | X(1) | - | |
RTC clock source | X | X(1,2) | X(2) | |
WDT oscillator | X | X | X | |
BOD oscillator(3) | X | X | X | |
CCL clock source | X | X(1) | - |
Note:
- Write the RUNSTDBY bit of the corresponding peripheral to enter an active state.
- In Standby sleep mode, only the RTC functionality requires the RUNSTDBY to be set to enter an active state. In Power-Down sleep mode, only the PIT functionality is available.
- Sampled mode only.
Wake-Up Source | Active in Sleep Mode | |||
---|---|---|---|---|
Idle | Standby | Power-Down | ||
PORT Pin interrupt | X | X | X(1) | |
TWI Address Match interrupt | X | X | X | |
BOD VLM interrupt | X | X | X | |
CCL interrupts | X | X(2,3) | X(3) | |
RTC interrupts | X | X(2,4) | X(4) | |
USART interrupts | X(5) | X(6) | - | |
TCAn interrupts | X | X(2) | - | |
TCBn interrupts | ||||
ADCn interrupts | ||||
ACn Compare interrupt | ||||
All other interrupts | X | - | - |
Note:
- The I/O pin must be configured according to Asynchronous Sensing Pin Properties in the PORT section.
- Set the RUNSTDBY bit of the corresponding peripheral to enter an active state.
- CCL can wake up the device if the path through LUTn is asynchronous
(FILTSEL=
0x0
and EDGEDET=0x0
in LUTnCTRLA register). - In Standby sleep mode, only the RTC functionality requires the RUNSTDBY to be set to enter an active state. In Power-Down sleep mode, only the PIT functionality is available.
- Start-of-Frame interrupt is only available in Standby sleep mode.
- In Standby sleep mode, only the Start-of-Frame interrupt will trigger Wake-Up from USART.