Datasheet

161
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
.
Table 84 shows the COMnx1:0 bit functionality when the WGMn3:0 bits are set to the
fast PWM mode.
Note: 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. See “Fast PWM Mode” on page 151. for more details.
Table 85 shows the COMnx1:0 bit functionality when the WGMn3:0 bits are set to the
phase correct and frequency correct PWM mode.
Note: A special case occurs when OCRnA/OCRnB/OCRnC equals TOP and
COMnA1/COMnB1//COMnC1 is set. See “Phase Correct PWM Mode” on page 153. for
more details.
Table 83. Compare Output Mode, non-PWM
COMnA1
COMnB1
COMnC1
COMnA0
COMnB0
COMnC0 Description
00Normal port operation, OCnA/OCnB/OCnC disconnected.
0 1 Toggle OCnA/OCnB/OCnC on compare match.
1 0 Clear OCnA/OCnB/OCnC on compare match (set output to low level).
1 1 Set OCnA/OCnB/OCnC on compare match (set output to high level).
Table 84. Compare Output Mode, Fast PWM
COMnA1
COMnB1
COMnC1
COMnA0
COMnB0
COMnC0 Description
00Normal port operation, OCnA/OCnB/OCnC disconnected.
01WGM13:0 = 14 or 15: Toggle OC1A on Compare Match, OC1B and
OC1C disconnected (normal port operation). For all other WGM1
settings, normal port operation, OC1A/OC1B/OC1C 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).
Table 85. Compare Output Mode, Phase Correct and Phase and Frequency Correct
PWM
COMnA1
COMnB1
COMnC1
COMnA0
COMnB0
COMnC0 Description
00Normal port operation, OCnA/OCnB/OCnC disconnected.
01WGM13:0 =9 or 11: Toggle OC1A on Compare Match, OC1B and
OC1C disconnected (normal port operation). For all other WGM1
settings, normal port operation, OC1A/OC1B/OC1C 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.