#include <Servo.h>

Servo myServo;

void setup() {
  myServo.attach(6);
}

void loop() {
  // myServo.write(0);
  // delay(1000);
  // myServo.write(180);
  // delay(1000);

  controlSpeed(10);
}

void controlSpeed(int spd) {
  for (int degree=0; degree<180; degree++) {
    myServo.write(degree);
    delay(spd);
  }
  for (int degree=180; degree>0; degree--) {
    myServo.write(degree);
    delay(spd);
  }
}