#include <Servo.h>

Servo s1;  // Create a servo object to control a servo

void setup() {
  s1.attach(9);  // Attaches the servo on pin 9 to the servo object
}

void loop() {
  // Sweep the servo from 0 degrees to 180 degrees
  for (int i = 0; i <= 180; i++) {
    s1.write(i);      // Tell servo to go to position in variable 'i'
    delay(15);        // Waits 15ms for the servo to reach the position
  }
  
  // Sweep the servo from 180 degrees back to 0 degrees
  for (int i = 180; i >= 0; i--) {
    s1.write(i);      // Tell servo to go to position in variable 'i'
    delay(15);        // Waits 15ms for the servo to reach the position
  }
}