[En-Nut-Discussion] Problem writing interrupt handler

[Pete Allinson]

Hi,

Can anyone help me with a problem I'm having writing code to start Timer 2 
running and then deal with overflow interrupts.

This is the code I'm using to start timer 2:

#define TIMER_COUNT   0xF0
#define TIMER_CTRL    0x01
static volatile u_short ticks_lo = 0;
static volatile u_short ticks_hi = 0;

void InitTicker(void)
{
     NutEnterCritical();
     /*
      * Initialize timer 2 and enable overflow interrupts.
      */
     outb(TCNT2, TIMER_COUNT);
     outb(TCCR2, TIMER_CTRL);
     sbi(TIMSK, 6);

     NutExitCritical();
}

And this is my interrupt handler:

SIGNAL(SIG_OVERFLOW2)
{
     /* Reset the timer value. */
     outb(TCNT2, TIMER_COUNT);

     if (++ticks_lo == 1000) {
         ticks_lo = 0;
#if 0
         /* If this code is in, NutSleep() in main() never returns */
         if (++ticks_hi == 1000) {
             ticks_hi = 0;
         }
#endif
     }
}

(The code is cribbed from irsony.c)

Things go wrong if the code between the #if  ... #endif is included.  For 
examples,  a call to NutSleep() in my main() never returns, NutGetSeconds() 
and NutGetMillis() don't seem to advance.
I've noticed that things also go wrong if 'ticks_lo' is a 'u_long' instead 
of a 'u_short'.

I'm using WinAVR and Nut/OS 3.9.2 to program an Ethernut 2.1 rev.B.

Regards,
Pete Allinson