ATMEGA48 datasheet(136/374 Pages) ATMEL

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136

2545J–AVR–12/06

ATmega48/88/168

14.11.9

TIFR1 – Timer/Counter1 Interrupt Flag Register

• Bit 7, 6 – Res: Reserved Bits

These bits are unused bits in the ATmega48/88/168, and will always read as zero.

• 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. Alternatively,

ICF1 can be cleared by writing a logic one to its bit location.

• Bit 4, 3 – Res: Reserved Bits

These bits are unused bits in the ATmega48/88/168, and will always read as zero.

• Bit 2 – OCF1B: Timer/Counter1, 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 exe-

cuted. Alternatively, OCF1B can be cleared by writing a logic one to its bit location.

• Bit 1 – OCF1A: Timer/Counter1, 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 exe-

cuted. Alternatively, OCF1A can be cleared by writing a logic one to its bit location.

• Bit 0 – 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 14-4 on page 132 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.

Bit

654

0x16 (0x36)

–

ICF1

–

OCF1B

OCF1A

TOV1

TIFR1

Read/Write

R/W

Initial Value

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