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135
2545T–AVR–05/11
ATmega48/88/168
16.11.7
ICR1H and ICR1L – Input capture register 1
The Input Capture is updated with the counter (TCNT1) value each time an event occurs on the
ICP1 pin (or optionally on the Analog Comparator output for Timer/Counter1). The Input Capture
can be used for defining the counter TOP value.
The Input Capture Register is 16-bit in size. To ensure that both the high and low bytes are read
simultaneously when the CPU accesses these registers, the access is performed using an 8-bit
temporary High Byte Register (TEMP). This temporary register is shared by all the other 16-bit
16.11.8
TIMSK1 – Timer/Counter1 interrupt mask register
Bit 7, 6 – Res: Reserved bits
These bits are unused bits in the Atmel ATmega48/88/168, and will always read as zero.
Bit 5 – ICIE1: Timer/Counter1, input capture interrupt enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally
enabled), the Timer/Counter1 Input Capture interrupt is enabled. The corresponding Interrupt
Bit 4, 3 – Res: Reserved bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
Bit 2 – OCIE1B: Timer/Counter1, output compare B match interrupt enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally
enabled), the Timer/Counter1 Output Compare B Match interrupt is enabled. The corresponding
TIFR1, is set.
Bit 1 – OCIE1A: Timer/Counter1, output compare A match interrupt enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally
enabled), the Timer/Counter1 Output Compare A Match interrupt is enabled. The corresponding
TIFR1, is set.
Bit 0 – TOIE1: Timer/Counter1, overflow interrupt enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally
enabled), the Timer/Counter1 Overflow interrupt is enabled. The corresponding Interrupt Vector
Bit
7
654
32
10
ICR1[15:8]
ICR1H
ICR1[7:0]
ICR1L
Read/write
R/W
Initial value
0
Bit
7654
3
2
1
0
–
ICIE1
–
OCIE1B
OCIE1A
TOIE1
TIMSK1
Read/write
R
R/W
R
R/W
Initial value
0000
0