#include <Servo.h>

Servo myservo;
int servoPin = 3;
int delayTime = 10;  // Delay between each rotation step (in milliseconds)

void setup() {
  myservo.attach(servoPin);
}

void loop() {
  for (int i= 0; i<= 180; i++) {
    myservo.write(i);
    delay(delayTime);
  }

  for (int  i= 180; i>= 0; i--) {
    myservo.write(i);
    delay(delayTime);
  }
}