
109
8006K–AVR–10/10
ATtiny24/44/84
Table 12-3 shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the fast
PWM 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.
“Fast PWMTable 12-4 shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the phase
correct or the phase and frequency correct, PWM mode.
Note:
1. A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set.
Table 12-2.
Compare Output Mode, non-PWM
COM1A1/COM1B1
COM1A0/COM1B0
Description
0
Normal port operation, OC1A/OC1B disconnected.
0
1
Toggle OC1A/OC1B on Compare Match.
10
Clear OC1A/OC1B on Compare Match (Set output to
low level).
11
Set OC1A/OC1B on Compare Match (Set output to
high level).
Table 12-3.
Compare Output Mode, Fast
PWM(1)COM1A1/COM1B1
COM1A0/COM1B0
Description
0
Normal port operation, OC1A/OC1B disconnected.
01
WGM13=0: Normal port operation, OC1A/OC1B
disconnected.
WGM13=1: Toggle OC1A on Compare Match, OC1B
reserved.
10
Clear OC1A/OC1B on Compare Match, set
OC1A/OC1B at BOTTOM (non-inverting mode)
11
Set OC1A/OC1B on Compare Match, clear
OC1A/OC1B at BOTTOM (inverting mode)
Table 12-4.
Compare Output Mode, Phase Correct and Phase & Frequency Correct
PWM(1)COM1A1/COM1B1
COM1A0/COM1B0
Description
0
Normal port operation, OC1A/OC1B disconnected.
01
WGM13=0: Normal port operation, OC1A/OC1B
disconnected.
WGM13=1: Toggle OC1A on Compare Match, OC1B
reserved.
10
Clear OC1A/OC1B on Compare Match when up-
counting. Set OC1A/OC1B on Compare Match when
downcounting.
11
Set OC1A/OC1B on Compare Match when up-
counting. Clear OC1A/OC1B on Compare Match
when downcounting.