:( To update my last, I was using generic ATMEGA x Timers, and this is where my problems happened, missing 6 and 7 prescaler values. I now find ATMEGA64(A)(L)/128(A), and with this the prescalers is correct. Was a bit confusing to find, but my fault, and you're GOOD ! Thanks to the developers Peter

:D I use AVR atmega128, and the timer calculator is a good tool, but I have discovered that TimerCounter0 uses prescaler values up to 7 (for divide by 1024). Shown here are times to counter overflow : Hz time ' CK0_STOP = 0 ' CK0_DIV1 = 1 ' 62500 16 us ' CK0_DIV8 = 2 ' 7812 128 us ' CK0_DIV32 = 3 ' ...