13.8.6.3.3 Sleep Mode Controller
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 in SUPC controller
is set. Before
entering Standby or Backup mode, the software must ensure
that the INTFLAG.SLEEPRDY bit
is set.
Mode | Mode Entry | Wake-Up Sources |
---|---|---|
IDLE | SLEEPCFG.SLEEPMODE = IDLE _n | Synchronous(2) (APB, AHB), asynchronous (1) |
STANDBY | SLEEPCFG.SLEEPMODE = STANDBY | Synchronous(3), Asynchronous |
BACKUP | SLEEPCFG.SLEEPMODE = BACKUP | Backup reset detected by the RSTC |
Note:
- Asynchronous: Interrupt generated on generic clock, external clock or external event.
- Synchronous: Interrupt generated on the APB clock.
- 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 and backup) and their effect on the clocks activity, the regulator and the NVM state are described in the table and the sections below. Refer to Power Domain Controller for the power domain gating effect.
Mode | Main clock | CPU | AHBx and APBx clock | GCLK clocks | Oscillators | Regulator | NVM | |
---|---|---|---|---|---|---|---|---|
ONDEMAND = 0 | ONDEMAND = 1 | |||||||
Active | Run | Run | Run | Run(3) | Run | Run if requested | MAINVREG | active |
IDLE | Run | Stop | Stop(1) | Run(3) | Run | Run if requested | MAINVREG | active |
STANDBY | Stop(1) | Stop | Stop(1) | Stop(1) | Run if requested or RUNSTDBY=1 | Run if requested | MAINVREG in low power mode | Ultra Low- power |
BACKUP | Stop | Stop | Stop | Stop | Stop | Stop | Backup regulator (ULPVREG) | OFF |
Note:
- Running if requested by peripheral during SleepWalking.
- Running during SleepWalking.
- Following On-Demand Clock Request principle.