The RTC supports two types of interrupts:
- ALARM interrupt. This interrupt is generated when
the configured date or time in the corresponding
ALARM registers is reached. This interrupt is
activated and deactivated by setting the IT_ALARM
bit. It is important to set the IT_ALARM = 0 to
deactivate the alarm interrupt prior to configuring
the ALARM registers to prevent the interrupt from
mis-firing.
- TIMER interrupt. This interrupt is generated when
the periodic time (day, hour, minute, second) set in
the EVERY bits of the RTC_INTERRUPTS register is
reached. The first of the periodic interrupt occurs
when the RTC counter reaches the next day, hour,
minute, or second counter value. For example, if a
timer interrupt is set for every hour at 2:59 AM,
the first interrupt occurs at 3:00 AM instead of
3:59 AM. This interrupt is activated and deactivated
by setting the IT_TIMER bit. It is important to set
the IT_TIMER = 0 to disable the timer interrupt
prior to configuring the periodic time value to
prevent the interrupt from mis-firing.
Both types of the RTC interrupts can be used to
wake-up the device from the STANDBY state or the LP_STANDBY state when they are not
masked.