18.6.3.3.2 STANDBY Mode

The STANDBY mode is the lowest power configuration while keeping the state of the logic and the content of the RAM.

In this mode, all clocks are stopped except those configured to be running sleepwalking tasks. The clocks can also be active on request or at all times, depending on their on-demand and run-in-standby settings. Either synchronous (CLK_APBx or CLK_AHBx) or generic (GCLK_x) clocks or both can be involved in sleepwalking tasks. This is the case when for example the SERCOM RUNSTDBY bit is written to '1'.

• Entering STANDBY mode: This mode is entered by executing the WFI instruction after writing the Sleep Mode bit in the Sleep Configuration register (SLEEPCFG.SLEEPMODE=STANDBY). The SLEEPONEXIT feature is also available as in IDLE mode.
• Exiting STANDBY mode: Any peripheral able to generate an asynchronous interrupt can wake up the system. For example, a peripheral running on a GCLK clock can trigger an interrupt. When the enabled asynchronous wake-up event occurs and the system is woken up, the device will either execute the interrupt service routine or continue the normal program execution according to the Priority Mask Register (PRIMASK) configuration of the CPU.

Refer to the section about the Power Domain Controller for the RAM state.

The regulator operates in low-power mode by default and switches automatically to the normal mode in case of a sleepwalking task requiring more power. It returns automatically to low power mode when the sleepwalking task is completed.