#include <Servo.h>
Servo myservo;

int pos=0;

void setup() {
  // put your setup code here, to run once:
  myservo.attach(9);
}

void loop() {
  // put your main code here, to run repeatedly:
  for (pos=0; pos<=180; pos++){
    myservo.write(pos);
    delay(15);
  }
  for(pos=180; pos>=0; pos--){
    myservo.write(pos);
    delay(15); 
  }
}