#include <Servo.h>
Servo myServo;

int const potPin = A0;
int potVal;
int angle;

void setup()
{
  // put your setup code here, to run once:
myServo.attach(9);
Serial.begin(9600);
}
void loop()
{
  // put your main code here, to run repeatedly:
for(int angle= 0; angle <180; angle++)
{
myServo.write(angle);
delay(15);
}
for(int angle= 179; angle >0; angle--)
{
  myServo.write(angle);
  delay(15);
}
}