void setup() {
pinMode(4, OUTPUT);
  // setup timer0
  TCCR0A  = 0x23;         // Fast PWM, output on OC0A and OC0B pins
  TCCR0B  = 0x09;         // /8 prescaling, loop on OC0A match
  OCR0A   = 1;
  OCR0B   = 0;
}

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

}