Interval Timer Core Interrupt for Nios II

Initialize the interrupt in your main application code this way:

  // register the timer irq to be serviced by handle_timer_interrupt() function 
 alt_irq_register(SYS_CLK_TIMER_IRQ, 0, handle_timer_interrupt);
 // activate the time
 IOWR_ALTERA_AVALON_TIMER_CONTROL(SYS_CLK_TIMER_BASE, 
                 ALTERA_AVALON_TIMER_CONTROL_CONT_MSK  
               | ALTERA_AVALON_TIMER_CONTROL_START_MSK
               | ALTERA_AVALON_TIMER_CONTROL_ITO_MSK);

void handle_timer_interrupt(void*p, alt_u32 param)
{
   // clear irq status in order to prevent retriggering
   IOWR_ALTERA_AVALON_TIMER_STATUS(SYS_CLK_TIMER_BASE, 0);
   // your isr code here
   // ....
}