According pag. 131 of ATmega168 d/s, by setting
COM1A1/COM1A0 bits=2
(Clear OC1A/OC1B on Compare Match when upcounting.
Set OC1A/OC1B on Compare Match when
downcounting)
while by setting:
COM1A1/COM1A0 bits=3, (Set OC1A/OC1B on Compare Match when upcounting.
Clear OC1A/OC1B on Compare Match
when downcounting)
The first option should be result in a inverted wave, while the second option should be result in a "non inverted" wave
Are you agree?