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XMEGA A [MANUAL]
8077I–AVR–11/2012
18.2.3 Power Domains
For devices where the RTC32 is located in the VBAT power domain, the battery backup feature enables the RTC32 to also
function with no main VCC available. A dynamic power switch is used to automatically switch from the VCC domain to the
VBAT domain if VCC falls below the operating voltage level for the device. When the VCC voltage is restored, the power is
automatically switched back to VCC.
18.2.4 Interrupts and Events
The RTC32 can generate both interrupts and events. The RTC32 will give a compare interrupt request and/or event at
the next count after the counter value equals the compare register value. The RTC32 will give an overflow interrupt
request and/or event at the next count after the counter value equals the period register value. The overflow will also
reset the counter value to zero.
Due to the asynchronous clock domains, events will be generated only for every third overflow or compare match if the
period register is zero. If the period register is one, events will be generated only for every second overflow or compare
match. When the period register is equal to or above two, events will trigger at every overflow or compare match, just as
the interrupt request.