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Rev. 5.00, 09/03, page 395 of 760
Bit 8—Underflow Flag (UNF): Status flag that indicates occurrence of a TCNT underflow.
Bit 8: UNF Description
0 TCNT has not underflowed
Clearing condition: When 0 is written to UNF (Initial value)
1 TCNT has underflowed
Setting condition: When TCNT underflows
*
Note: * Contents do not change when 1 is written to UNF.
Bits 7 and 6—Input Capture Control (ICPE1, ICPE0): A function of channel 2 only:
determines whether the input capture function can be used, and when used, whether or not to
enable interrupts.
When using this input capture function it is necessary to set the TCLK pin to input mode with the
TCOE bit in the TOCR register. Additionally, use the CKEG bit to designate use of either the
rising or falling edge of the TCLK pin to set the value in TCNT2 in the input capture register
(TCPR2).
Bit 7: ICPE1 Bit 6: ICPE0 Description
0 0 Input capture function is not used (Initial value)
1 Reserved (Setting prohibited)
1 0 Input capture function is used. Interrupt due to ICPF (TICPI2)
is not enabled
1 Input capture function is used. Interrupt due to ICPF (TICPI2)
is enabled
Bit 5—Underflow Interrupt Control (UNIE): Controls enabling of interrupt generation when
the status flag (UNF) indicating TCNT underflow has been set to 1.
Bit 5: UNIE Description
0 Interrupt due to UNF (TUNI) is not enabled (Initial value)
1 Interrupt due to UNF (TUNI) is enabled