#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#define F_OSC 4000000
//#define F_CPU 8000000

void delay_ms(unsigned short ms) {
        unsigned short outer1, outer2;
        outer1 = 200;
        while (outer1) {
                outer2 = 1000;
                while (outer2) {
                        while ( ms ) { ms--; asm volatile("nop"); }
                        outer2--;
                }
                outer1--;
        }
}

int main(void){
        unsigned short duration=5000;
        //SET OUTPUT PINS
        DDRD |= (1 << PD6);
        DDRD |= (1 << PD5);
        DDRD |= (1 << PD4);

        while (1) {
                PORTD |= (1 << PD6);
                _delay_ms(duration);
                PORTD &= ~(1 << PD6);
                PORTD |= (1 << PD4);
                _delay_ms(duration);
                PORTD &= ~(1 << PD4);
        }
        return 0;
}