4.2 Example

Round-robin Interrupt Scheduling configuration

// io.h includes the device header file with register and vector defines
#include <avr/io.h>
// interrupt.h contains the ISR related content
#include <avr/interrupt.h>

void round_robin_interrupt_scheduling_example(void) {
    // Set the Round-robin Scheduling Enable bit.
    CPUINT.CTRLA |= CPUINT_LVL0RR_bm;

    // Example on how to shift the initial interrupt priority.
    CPUINT.LVL0PRI = PORTA_PORT_vect_num;

    // Enable global interrupts
    sei();
}

ISR(PORTA_PORT_vect){
    // This interrupt will initially have lowest priority, however
    // that will change since the LVL0PRI will be updated by the interrupt 
    // controller each time an interrupt is executed.
}