#include <Servo.h>

Servo myservo;  // create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 0;    // variable to store the servo position

void setup() {
  myservo.attach(27);  // attaches the servo on pin 9 to the servo object
}

void loop() {
  for (pos = 0; pos <= 90; pos += 1) { // goes from 0 degrees to 90 degrees
     myservo.write(pos);             // tell servo to go to position in variable 'pos'
    delay(1500);                       // waits 1500ms for the servo to reach the position
  }
   for (pos = 90; pos <= 180; pos += 1) { // goes from 90 degrees to 180 degrees
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(1500);                       // waits 1500ms for the servo to reach the position
  }
  
  for (pos = 180; pos >= 0; pos -= 1) { // goes from 90 degrees to 180 degrees
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(1500);                       // waits 1500ms for the servo to reach the position
  }
}