93
ATtiny25/45/85 [DATASHEET]
2586Q–AVR–08/2013
12.3.8
TIFR – Timer/Counter Interrupt Flag Register
Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the ATtiny25/45/85 and always reads as zero.
Bit 6 – OCF1A: Output Compare Flag 1A
The OCF1A bit is set (one) when compare match occurs between Timer/Counter1 and the data value in OCR1A -
Output Compare Register 1A. OCF1A is cleared by hardware when executing the corresponding interrupt handling
vector. Alternatively, OCF1A is cleared, after synchronization clock cycle, by writing a logic one to the flag. When
the I-bit in SREG, OCIE1A, and OCF1A are set (one), the Timer/Counter1 A compare match interrupt is executed.
Bit 5 – OCF1B: Output Compare Flag 1B
The OCF1B bit is set (one) when compare match occurs between Timer/Counter1 and the data value in OCR1B -
Output Compare Register 1A. OCF1B is cleared by hardware when executing the corresponding interrupt handling
vector. Alternatively, OCF1B is cleared, after synchronization clock cycle, by writing a logic one to the flag. When
the I-bit in SREG, OCIE1B, and OCF1B are set (one), the Timer/Counter1 B compare match interrupt is executed.
Bit 2 – TOV1: Timer/Counter1 Overflow Flag
In normal mode (PWM1A=0 and PWM1B=0) the bit TOV1 is set (one) when an overflow occurs in Timer/Counter1.
The bit TOV1 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively,
TOV1 is cleared, after synchronization clock cycle, by writing a logical one to the flag.
In PWM mode (either PWM1A=1 or PWM1B=1) the bit TOV1 is set (one) when compare match occurs between
Timer/Counter1 and data value in OCR1C - Output Compare Register 1C.
When the SREG I-bit, and TOIE1 (Timer/Counter1 Overflow Interrupt Enable), and TOV1 are set (one), the
Timer/Counter1 Overflow interrupt is executed.
Bit 0 – Res: Reserved Bit
This bit is a reserved bit in the ATtiny25/45/85 and always reads as zero.
Bit
7
6
5
4
3
2
1
0
–OCF1A
OCF1B
OCF0A
OCF0B
TOV1
TOV0
–
TIFR
Read/Write
R
R/W
R
Initial value
0