AVR-Chat

Marc R.J. Brevoort wrote:
> I had set the prescaler to 256, assuming this would
> result in a timer of 8MHz/256=31250 Hz, and set
> TCNT0 to 254 (one overflow every 2 ticks, or roughly
> 15625 times per second) which would give me approx.
> 512 cycles to calculate the wave.
>
> Right now, I've set:
>
> TCCR0B to 0<<CS02|0<<CS01|1<<CS00 (no prescaling)
> and
> TCNT0 to 255 (overflow on next tick)
> and
> TIMSK=(1<<TOIE) (enable counter overflow int).

    For one interrupt every 1/31250Hz, I'd use:

    TCCR0A = 1<<WGM1  (CTC mode)
    TCCR0B = 1<<CS01   (8MHz/8)
    OCR0A = ((8MHz/8)/31250Hz)-1 = 32-1
    TIMSK = 1<<OC1E0A
    TCNT0 = don't care

    Mark Jordan