TINY13 PWM behavior stumps me.

I have a chunk of code that operates fine on larger AVR8s, but does not 
seem to operate on the T13.  Just wondering if it's me (could be, this 
is the first time I have used such a small AVR8), or the uC...

A snippet:

static volatile uint8_t i = 0;

int main(void) {
   DDRB = _BV(PB0) | _BV(PB1);
   TCCR0A = _BV(COM0A1) | _BV(COM0B1) | _BV(WGM00);
   TCCR0B = _BV(CS00);
   while (1) {

       while(!(TIFR0 & _BV(OCF0A))) ;
       TIFR0 |= _BV(OCF0A);
       if(i == 2) {
         i = 0;
       }
           OCR0A = 192;
         else
           OCR0A = 64;
       i++;
}

When I run this on a larger AVR8, I get 192/64 split on the output, but 
the T13 just shows the first value on the OCR0A output (192, in this case).

I changed the loop to be:

   while (1) {
     for(i = 0; i < 2;i++) {
       while(!(TIFR0 & _BV(OCF0A))) ;
       TIFR0 |= _BV(OCF0A);
         if(!i)
           PWM1_OCR = 192;
         else
           PWM1_OCR = 64;
       }
}

And that shows random values (64 or 192, but in random arrangements, not 
alternating...)

Obviously, this code is non optimal (my original code was an ISR), but I 
thought I'd try to simplify to see if I could figure out the issue.

JIm


-- Jim Brain [email protected] www.jbrain.com