int LED = 2;
int buzzer = 10;
int trigerpin = 12;
int echo = 13;
int duration;
int distance;
int pitch = 262;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(LED, OUTPUT);
pinMode(buzzer, OUTPUT);
pinMode(trigerpin, OUTPUT);
pinMode(echo, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
//create sound wave pulse
digitalWrite(trigerpin, LOW);
delayMicroseconds(2);
digitalWrite(trigerpin, HIGH);
delayMicroseconds(10);
digitalWrite(trigerpin, LOW);
delayMicroseconds(2);
//duration
duration = pulseIn(echo,HIGH);
//distance
distance = (duration/2)*0.0343;
//logic
if (distance<200){
  digitalWrite(LED, HIGH);
  tone(buzzer, pitch);
  delay(300);
  digitalWrite(LED, LOW);
  noTone(buzzer);
  delay(300);
  }
  else{
  digitalWrite(LED, LOW);
  noTone(buzzer);
  }
}