178
8210C–AVR–09/11
Atmel AVR XMEGA D
15.3.10
COMPL – Compare Register Low
The COMPH and COMPL register pair represent the 16-bit value, COMP. COMP is constantly
compared with the counter value (CNT). A compare match will set COMPIF in the INTFLAGS
register. Reading and writing 16-bit values requires special attention. Refer
for details.
Due to synchronization between the RTC clock and system clock domains, there is a latency of
two RTC clock cycles from updating the register until this has an effect. Application software
needs to check that the SYNCBUSY flag in the
”STATUS – Status register” on page 175
is
cleared before writing to this register.
If the COMP value is higher than the PER value, no RTC compare match interrupt requests or
events will ever be generated.
• Bit 7:0 – COMP[7:0]: Compare Register Low
These bits hold the LSB of the 16-bit RTC compare value.
15.3.11
COMPH – Compare Register High
• Bit 7:0 – COMP[15:8]: Compare Register High
These bits hold the MSB of the 16-bit RTC compare value.
Bit
7
6
5
4
3
2
1
0
COMP[7:0]
COMPL
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COMP[15:8]
COMPH
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0