20.6.2. Principle of Operation
In active mode, all clock domains and power domains are active, allowing software execution and
peripheral operation. The PM Sleep Mode Controller allows to save power by choosing between different
sleep modes depending on application requirements, see
.
The PM Performance Level Controller allows to optimize either for low power consumption or high
performance.
The PM Power Domain Controller allows to reduce the power consumption in standby mode even further.
20.6.3. Basic Operation
20.6.3.1. Initialization
After a power-on reset, the PM is enabled, the device is in ACTIVE mode, the performance level is PL0
(the lowest power consumption) and all the power domains are in active state.
20.6.3.2. Enabling, Disabling and Resetting
The PM is always enabled and can not be reset.
20.6.3.3. Sleep Mode Controller
A Sleep mode is entered by executing the Wait For Interrupt instruction (WFI). The Sleep Mode bits in the
Sleep Configuration register (SLEEPCFG.SLEEPMODE) select the level of the sleep mode.
Note:
A small latency happens between the store instruction and actual writing of the SLEEPCFG
register due to bridges. Software must ensure that the SLEEPCFG register reads the desired value
before issuing a WFI instruction.
Note:
After power-up, the MAINVREG low power mode takes some time to stabilize. Once stabilized,
the INTFLAG.SLEEPRDY bit is set. Before entering Standby or Backup mode, software must ensure that
the INTFLAG.SLEEPRDY bit is set.
Table 20-1. Sleep Mode Entry and Exit Table
Mode
Mode Entry
Wake-Up Sources
IDLE
SLEEPCFG.SLEEPMODE = IDLE
(APB, AHB), asynchronous
STANDBY
SLEEPCFG.SLEEPMODE =
STANDBY
BACKUP
SLEEPCFG.SLEEPMODE =
BACKUP
Backup reset detected by the RSTC
OFF
SLEEPCFG.SLEEPMODE = OFF
External Reset
Note:
1.
Asynchronous: interrupt generated on generic clock, external clock, or external event.
2.
Synchronous: interrupt generated on the APB clock.
3.
Synchronous interrupt only for peripherals configured to run in standby.
Note:
The type of wake-up sources (synchronous or asynchronous) is given in each module interrupt
section.
The sleep modes (idle, standby, backup, and off) and their effect on the clocks activity, the regulator and
the NVM state are described in the table and the sections below.
Atmel SAM L22G / L22J / L22N [DATASHEET]
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