#include <Servo.h>
#define trigPin 5
#define echoPin 6
Servo servo_9;
int sound = 400;
int pos = 0;

void setup() {
Serial.begin (9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(11, OUTPUT);
servo_9.attach(9);
}
void loop() {

long duration, distance;
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;

  Serial.println(distance);
 
  if (distance < 20)
    {
  pos = 90;
  tone(11, sound,200);
  servo_9.write(pos);

  delay(500); // Wait for 15 millisecond(s)
    }
 
  else
    {
    pos = 0;
  servo_9.write(pos);
  delay(15); // Wait for 15 millisecond(s)
  }
  

  delay (500);
}