#define myservo 5 // the pin the servo is on

void setup() {
  pinMode(myservo, OUTPUT);
}

void loop() {
  for (int x = 0; x < 50; x++) {
    digitalWrite(myservo, HIGH);
    delayMicroseconds(500);
    digitalWrite(myservo, LOW);
    delayMicroseconds(19500);
  }
  for (int x = 0; x < 50; x++) {
    digitalWrite(myservo, HIGH);
    delayMicroseconds(2500);
    digitalWrite(myservo, LOW);
    delayMicroseconds(17500);
  }
}