Re: [avr-gcc-list] lack of interruption

[E. Weddington]

jeffrey traer bernstein wrote:

> can't quite figure out why my interrupt isn't interrupting... anybody
> have any suggestions?
>
> it's on an atmega16
>
>
>
> #include <avr/io.h>
> #include <avr/interrupt.h>
>
> void SIGNAL( SIG_OVERFLOW0 )
> {
>    PORTA = 0x00;
> }
>
>
> int main()
> {
>  DDRA = 0xff;
>  PORTA = 0x01;  
>
>  TIMSK = _BV(TOIE0);
>  TCCR0 = 0x05;
>  TCNT0 = 0;
>
>  sei();
>
>  while ( 1 );
>
>  return 0;
> }
>
>  
According to the datasheet:

"In normal operation the Timer/Counter Overflow Flag
(TOV0) will be set in the same timer clock cycle as the TCNT0 becomes zero."

I'm not sure if this will help but, but try changing it:

 TIMSK = _BV(TOIE0);   // Enable interrupt.
 TCNT0 = 0;            // Clear timer.
 TCCR0 = 0x05;         // Start timer with div 1024 prescaler.