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XMEGA A [MANUAL]
8077I–AVR–11/2012
18.3
Register Descriptions
18.3.1 CTRL – Control register
Bit 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
Bit 0 – ENABLE: Enable
Setting this bit enables the RTC32. The synchronization time between the RTC32 and the system clock domains is one
half RTC32 clock cycle from writing the register until this has an effect in the RTC32 clock domain; i.e., until the RTC32
starts.
For the RTC32 to start running, the PER register must also be set to a value different from zero.
18.3.2 SYNCCTRL – Synchronisation Control/Status register
Bit 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
Bit 4 – SYNCCNT: Enable Synchronization of the CNT Register
Setting this bit will start synchronization of the CNT register from the RTC32 clock to the system clock domain. The bit is
automatically cleared when synchronization is done.
Bit 3:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
Bit 0 – SYNCBUSY: Synchronization Busy Flag
This flag is set when the CTRL or CNT register is busy synchronizing from the system clock to the RTC32 clock domain.
The CTRL register synchronization is triggered when it is written. The CNT register is synchronized when the most-
significant byte of the register is written.
Bit
76543210
+0x00
–
ENABLE
Read/Write
RRRRRRR
R/W
Initial Value
00000000
Bit
765
4
3
2
1
0
+0x01
–
SYNCCNT
–
SYNCBUSY
Read/Write
R
R/W
R
R/W
Initial Value
0