#define PIN6 6

void setup() {
  // put your setup code here, to run once:
  DDRD = 1 < PIN6;
  pinMode(6, OUTPUT);
  TCCR0A = (1<<COM0A1);
  TCCR0A |= (1<<WGM01) | (1<<WGM00);
  TCCR0B = (1<<CS01);
  OCR0A = 250; //When the value reaches 250, an interrupt occur and TImer becomes zero
}

void loop() {
  // put your main code here, to run repeatedly:
}