20.5.1 Force Output Compare
In non-PWM waveform generation modes, the match output of the comparator can be forced by writing a '1' to the Force Output Compare (TCCR0C.FOC0x) bit. Forcing compare match will not set the OCF0x Flag or reload/clear the timer, but the OC0x pin will be updated as if a real compare match had occurred (the TCCR0A.COM0x[1:0] bits define whether the OC0x pin is set, cleared or toggled).