encoder.c

#include <avr/io.h>

#include <avr/interrupt.h>

#define XTAL        4e6                 

#define LEDS_DDR    DDRB

#define LEDS        PORTB               

void encode_init( void )            

{

  TCCR0 = (1<<WGM01) | (1<<CS01) | (1<<CS00);     // CTC, XTAL / 64

  OCR0 = (uint8_t)(XTAL / 64.0 * 1e-3 - 0.5);       // 1ms

  TIMSK |= 1<<OCIE0;

}

ISR( TIMER0_COMP_vect )             

{

  LEDS = 0x00;

}

int main( void )

{

  LEDS_DDR = 0xFF;

  LEDS=0xFF;

  encode_init();

  sei();

  while(1);

}