Datasheet

Table 20-3 Compare Output Mode, Fast PWM
COMnA1/
COMnB1/
COMnC1
COMnA0/
COMnB0/
COMnC0
Description
0 0 Normal port operation, OCnA/OCnB/OCnC disconnected.
0 1 WGMn3:0 = 15: Toggle OCnA on Compare Match, OCnB/OCnC
disconnected (normal port operation). For all other WGMn
settings, normal port operation, OCnA/OCnB/OCnC disconnected.
1 0 Clear OCnA/OCnB/OCnC on compare match, set OCnA/OCnB/
OCnC at BOTTOM, (non-inverting mode)
1 1 Set OCnA/OCnB/OCnC on compare match, clear OCnA/OCnB/
OCnC at BOTTOM, (inverting mode)
Note: 1. A special case occurs when OCRnA/OCRnB/OCRnC equals TOP and COMnA1/COMnB1/
COMnC1 is set. In this case the compare match is ignored, but the set or clear is done at BOTTOM.
Refer to Fast PWM Mode on page 150 for details.
The table below shows the COMnx1:0 bit functionality when the WGMn3:0 bits are set to the phase
correct and frequency correct PWM mode.
Table 20-4 Compare Output Mode, Phase Correct and Phase and Frequency Correct PWM
COMnA1/
COMnB1/
COMnC1
COMnA0/
COMnB0/
COMnC0
Description
0 0 Normal port operation, OCnA/OCnB/OCnC disconnected.
0 1 WGMn3:0 = 9 or 11: Toggle OCnA on Compare Match, OCnB/
OCnC disconnected (normal port operation). For all other WGMn
settings, normal port operation, OCnA/OCnB/OCnC disconnected.
1 0 Clear OCnA/OCnB/OCnC on compare match when up-counting.
Set OCnA/OCnB/OCnC on compare match when downcounting.
1 1 Set OCnA/OCnB/OCnC on compare match when up-counting.
Clear OCnA/OCnB/OCnC on compare match when downcounting.
Note: 1. A special case occurs when OCRnA/OCRnB/OCRnC equals TOP and COMnA1/COMnB1/
COMnC1 is set. Refer to Phase Correct PWM Mode on page 152 for details.
Bits 1:0 – WGM1n: Waveform Generation Mode [n = 1:0]
Combined with the WGMn3:2 bits found in the TCCRnB 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, refer to the table below. 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. (Refer to Modes of Operation on page 148).
Atmel ATmega64A [DATASHEET]
Atmel-8160E-ATmega64A_Datasheet_Complete-09/2015
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