Datasheet
20.15.9 TC1 Interrupt Flag Register
Name: TIFR1
Offset: 0x36
Reset: 0x00
Property: When addressing as I/O register: address offset is 0x16
When addressing I/O registers as data space using LD and ST instructions, the provided offset must be
used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an
I/O address offset within 0x00 - 0x3F.
Bit 7 6 5 4 3 2 1 0
ICF1 OCF1B OCF1A TOV1
Access
R/W R/W R/W R/W
Reset 0 0 0 0
Bit 5 – ICF1 Timer/Counter 1, Input Capture Flag
This flag is set when a capture event occurs on the ICP1 pin. When the Input Capture Register (ICR1) is
set by the WGM1[3:0] to be used as the TOP value, the ICF1 flag is set when the counter reaches the
TOP value.
ICF1 is automatically cleared when the input capture interrupt vector is executed. Alternatively, ICF1 can
be cleared by writing a logic one to its bit location.
Bit 2 – OCF1B Timer/Counter 1, Output Compare B Match Flag
This flag is set in the timer clock cycle after the counter (TCNT1) value matches the Output Compare
Register B (OCR1B).
Note that a Forced Output Compare (FOC1B) strobe will not set the OCF1B flag.
OCF1B is automatically cleared when the output compare match B interrupt vector is executed.
Alternatively, OCF1B can be cleared by writing a logic one to its bit location.
Bit 1 – OCF1A Timer/Counter 1, Output Compare A Match Flag
This flag is set in the timer clock cycle after the counter (TCNT1) value matches the Output Compare
Register A (OCR1A).
Note that a Forced Output Compare (FOC1A) strobe will not set the OCF1A flag.
OCF1A is automatically cleared when the output compare match A interrupt vector is executed.
Alternatively, OCF1A can be cleared by writing a logic one to its bit location.
Bit 0 – TOV1 Timer/Counter 1, Overflow Flag
The setting of this flag is dependent on the WGM1[3:0] bits setting. In Normal and CTC modes, the TOV1
flag is set when the timer overflows. Refer to the Waveform Generation mode bit description for the TOV1
flag behavior when using another WGM1[3:0] bit setting.
TOV1 is automatically cleared when the timer/counter 1 overflow interrupt vector is executed.
Alternatively, TOV1 can be cleared by writing a logic one to its bit location.
ATmega48PA/88PA/168PA
16-bit Timer/Counter1 (TC1) with PWM
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 194