Timer/Counter Interrupt Flag
Register – TIFR
Bit
7
OCF2
R/W
0
6
TOV2
R/W
0
5
4
OCF1A
R/W
0
3
OCF1B
R/W
0
2
TOV1
R/W
0
1
OCF0
R/W
0
0
TOV0
R/W
0
ICF1
R/W
0
TIFR
Read/Write
Initial Value
Note:
This register contains flag bits for several Timer/Counters, but only Timer1 bits are
described in this section. The remaining bits are described in their respective timer
sections.
• Bit 5 – ICF1: Timer/Counter1, 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 WGM13:0 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. Alter-
natively, ICF1 can be cleared by writing a logic one to its bit location.
• Bit 4 – OCF1A: Timer/Counter1, Output Compare A Match Flag
This flag is set in the timer clock cycle after the counter (TCNT1) value matches the Out-
put 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 3 – OCF1B: Timer/Counter1, Output Compare B Match Flag
This flag is set in the timer clock cycle after the counter (TCNT1) value matches the Out-
put 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 2 – TOV1: Timer/Counter1, Overflow Flag
The setting of this flag is dependent of the WGM13:0 bits setting. In normal and CTC
modes, the TOV1 flag is set when the timer overflows. Refer to Table 47 on page 106
for the TOV1 flag behavior when using another WGM13:0 bit setting.
TOV1 is automatically cleared when the Timer/Counter1 Overflow interrupt vector is
executed. Alternatively, TOV1 can be cleared by writing a logic one to its bit location.
110
ATmega16(L)
2466E–AVR–10/02
ATMEL [ ATMEL ]
