Datasheet

COM1A1/
COM1B1
COM1A0/
COM1B0
Description
1 0 Clear OC1A/OC1B on Compare Match, set OC1A/OC1B at
BOTTOM (non-inverting mode)
1 1 Set OC1A/OC1B on Compare Match, clear OC1A/OC1B at
BOTTOM (inverting mode)
Note:
1. A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set. In this
case the compare match is ignored, but the set or clear is done at BOTTOM. Refer to Fast PWM
Mode for details.
The table below shows the COM1x1:0 bit functionality when the WGM1[3:0] bits are set to the phase
correct or the phase and frequency correct, PWM mode.
Table 16-5. Compare Output Mode, Phase Correct and Phase and Frequency Correct PWM
COM1A1/
COM1B1
COM1A0/
COM1B0
Description
0 0 Normal port operation, OC1A/OC1B disconnected.
0 1 WGM1[3:0] = 9 or 11: Toggle OC1A on Compare Match, OC1B
disconnected (normal port operation). For all other WGM1 settings,
normal port operation, OC1A/OC1B disconnected.
1 0 Clear OC1A/OC1B on Compare Match when up-counting. Set
OC1A/OC1B on Compare Match when down-counting.
1 1 Set OC1A/OC1B on Compare Match when up-counting. Clear
OC1A/OC1B on Compare Match when down-counting.
Note:
1. A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set. Refer to
Phase Correct PWM Mode for details.
Bits 0, 1 – WGM10, WGM11: Waveform Generation Mode
Combined with the WGM1[3:2] bits found in the TCCR1B Register, these bits control the counting
sequence of the counter, the source for maximum (TOP) counter value, and what type of waveform
generation to be used. Modes of operation supported by the Timer/Counter unit are: Normal mode
(counter), Clear Timer on Compare match (CTC) mode, and three types of Pulse Width Modulation
(PWM) modes. (See Modes of Operation).
Table 16-6. Waveform Generation Mode Bit Description
Mode
WGM13 WGM12
(CTC1)
(1)
WGM11
(PWM11)
(1)
WGM10
(PWM10)
(1)
Timer/
Counter
Mode of
Operation
TOP Update of
OCR1x at
TOV1 Flag
Set on
0 0 0 0 0 Normal 0xFFFF Immediate MAX
1 0 0 0 1 PWM, Phase
Correct, 8-bit
0x00FF TOP BOTTOM
2 0 0 1 0 PWM, Phase
Correct, 9-bit
0x01FF TOP BOTTOM
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
172