Arduino Tiny

Using Arduino Microcontrollers
179

I'll try to look more closely at it tomorrow but I believe you have to set CTC1 in TCCR1...

TCCR1 =
(1 << CTC1)
| (0 << PWM1A)
| (0 << COM1A1) | (0 << COM1A0)
| (1 << CS13) | (0 << CS12) | (0 << CS11) | (0 << CS10);