#include <avr/io.h>
#include <util/delay.h>

void timer_init(void)
{
  DDRB |= (1 << PB1);
  TCCR1A |= (1 << WGM11) | (1 << COM1A1);
  TCCR1B |= (1 << WGM13) | (1 << WGM12) | (1 << CS11);
  ICR1 = 39999;
}

void set_angle(uint16_t angle)
{
  uint16_t pulse = 1000 + (angle * 1000) / 180;
  OCR1A = (pulse * (ICR1 + 1)) / 20000;
}

int main(void)
{
  timer_init();
  while(1)
  {
    set_angle(0);
    _delay_ms(1000);
    set_angle(90);
    _delay_ms(1000);
    set_angle(180);
    _delay_ms(1000);
  }
  return 0;
}