134
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
the fast PWM mode.
Note:
1. A special case occurs when OCRnA/OCRnB equals TOP and COMnA1/COMnB1 is set. In
this case the compare match is ignored, but the set or clear is done at BOTTOM.
See Sectionthe phase correct or the phase and frequency correct, PWM mode.
Note:
1. A special case occurs when OCRnA/OCRnB equals TOP and COMnA1/COMnB1 is set.
See Bit 1:0 – WGMn1:0: Waveform Generation Mode
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 wave-
Timer/Counter unit are: Normal mode (counter), Clear Timer on Compare match (CTC) mode,
Table 16-3.
Compare Output mode, fast PWM
COMnA1/COMnB1
COMnA0/COMnB0
Description
0
Normal port operation, OCnA/OCnB disconnected.
01
WGMn3:0 = 14 or 15: Toggle OC1A on Compare
Match, OC1B disconnected (normal port operation).
For all other WGM1 settings, normal port operation,
OC1A/OC1B disconnected.
10
Clear OCnA/OCnB on Compare Match, set
OCnA/OCnB at BOTTOM (non-inverting mode)
11
Set OCnA/OCnB on Compare Match, clear
OCnA/OCnB at BOTTOM (inverting mode)
Table 16-4.
Compare Output mode, phase correct and phase and frequency correct PWM
(1).COMnA1/COMnB1
COMnA0/COMnB0
Description
0
Normal port operation, OCnA/OCnB disconnected.
01
WGMn3:0 = 9 or 11: Toggle OCnA on Compare
Match, OCnB disconnected (normal port operation).
For all other WGM1 settings, normal port operation,
OC1A/OC1B disconnected.
10
Clear OCnA/OCnB on Compare Match when up-
counting. Set OCnA/OCnB on Compare Match when
downcounting.
11
Set OCnA/OCnB on Compare Match when up-
counting. Clear OCnA/OCnB on Compare Match
when downcounting.