25.6.6 Sleep Mode Operation
The RTC will continue to operate in any sleep mode where the source clock is active. The RTC interrupts can be used to wake up the device from a sleep mode. RTC events can trigger other operations in the system without exiting the sleep mode.
An interrupt request will be generated after the wake-up if the Interrupt Controller is configured accordingly. Otherwise the CPU will wake up directly, without triggering any interrupt. In this case, the CPU will continue executing right from the first instruction that followed the entry into sleep.
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