221
8331B–AVR–03/12
Atmel AVR XMEGA AU
18.3
Register Descriptions
18.3.1
CTRL – Control register
• Bit 7:3 – 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 2:0 – PRESCALER[2:0]: Clock Prescaling factor
These bits define the prescaling factor for the RTC clock according to
.
Bit
7
6
5
4
3
2
1
0
–
–
–
–
–
PRESCALER[2:0]
CTRL
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Table 18-1.
Real-time counter clock prescaling factor.
PRESCALER[2:0]
Group Configuration
RTC Clock Prescaling
000
OFF
No clock source, RTC stopped
001
DIV1
RTC clock / 1 (no prescaling)
010
DIV2
RTC clock / 2
011
DIV8
RTC clock / 8
100
DIV16
RTC clock / 16
101
DIV64
RTC clock / 64
110
DIV256
RTC clock / 256
111
DIV1024
RTC clock / 1024
