//create timing by timer0  overflow interrupt
/* timer 1ms = 16000*62.5ns (16MHz)
*  8 bit Timer --> Overflow after 256 clock cycles
* Prescaler  1,8,64
* Overflow after 16us,128us, 1024us 
*
* therefore Prescaler 64 used
*/ 
#include <avr/io.h>
#define F_CPU 16000000UL  //must be defined prior to delay.h
#include <avr/interrupt.h>
#define A  PORTB7
#define B  PORTB6
#define C  PORTB5
#define MAX 14
const uint8_t preloadValue = 6;	// magic number for correct timing
									// use simulator to find out
uint8_t signals[] ={0,0,1,1,1,6,4,4,4,4,4,4,0,0};
volatile uint8_t n; //Signalnr
void setup(); 
int main(){
	setup(); 
	sei(); 
	while(1){
	}
}
ISR (TIMER0_OVF_vect){
   PORTB = signals[n++]<<5; 
   TCNT0 = preloadValue; 
   n = n % 14; //periodic
}
void setup(){
  DDRB |= (1<<A)|(1<<B)|(1<<C); 	
  // Timer0 Overflow interrupt and Prescaler 64
  TIMSK0 |= (1<<TOIE0); 
  TCCR0B |= (1<<CS01)|(1<<CS00); 
}