132
7530J–AVR–03/12
Atmel ATmega48/88/168 Automotive
14.10.5
Output Compare Register 1 A – OCR1AH and OCR1AL
14.10.6
Output Compare Register 1 B – OCR1BH and OCR1BL
The Output Compare Registers contain a 16-bit value that is continuously compared with the
counter value (TCNT1). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC1x pin.
The Output Compare Registers are 16-bit in size. To ensure that both the high and low bytes are
written simultaneously when the CPU writes to these registers, the access is performed using an
8-bit temporary High Byte Register (TEMP). This temporary register is shared by all the other
14.10.7
Input Capture Register 1 – ICR1H and ICR1L
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
14.10.8
Timer/Counter1 Interrupt Mask Register – TIMSK1
Bit 7, 6 – Res: Reserved Bits
These bits are unused bits in the 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
76543210
OCR1A[15:8]
OCR1AH
OCR1A[7:0]
OCR1AL
Read/Write
R/W
Initial Value
00000000
Bit
76543210
OCR1B[15:8]
OCR1BH
OCR1B[7:0]
OCR1BL
Read/Write
R/W
Initial Value
00000000
Bit
76543210
ICR1[15:8]
ICR1H
ICR1[7:0]
ICR1L
Read/Write
R/W
Initial Value
00000000
Bit
7
6
543
2
1
0
–
ICIE1
–
OCIE1B
OCIE1A
TOIE1
TIMSK1
Read/Write
R
R/W
R
R/W
Initial Value
0