#include <Servo.h>

const byte servoPin = 3;

unsigned int defUs = 1472;  // sets initial pulse width (default angle) for servo (beteen 544 and 2400)
unsigned int usStep = 10;
const unsigned int minUs = 544;
const unsigned int maxUs = 2400;
const unsigned int speed = 1;  // step μs (1 slow to 100 fast)
bool dir;
unsigned int pos;

Servo servo;  // create servo object

void setup() {
  servo.attach(servoPin);  // attaches the servo on pin 3 to the servo object
  pos = defUs;             // initial position
}

void loop() {

  servo.writeMicroseconds(pos);

  if (dir) {
    if (pos <= maxUs) {
      pos += speed;
    } else {
      dir = false;
    }
  } else {
    if (pos >= minUs) {
      pos -= speed;
    } else {
      dir = true;
    }
  }
  delay(15); // loop speed determines the maximum servo speed limit
}