#define trig 15
#define echo 5
#define buzzer 23
long duration,distance;
void setup() {
  // put your setup code here, to run once:
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(115200);
  
}

void loop() {
  // put your main code here, to run repeatedly:
   // this speeds up the simulatio
   digitalWrite(trig,LOW);
   delayMicroseconds(2);
   digitalWrite(trig,HIGH);
   delayMicroseconds(10);
   digitalWrite(trig,LOW);
   duration=pulseIn(echo,HIGH);
   distance=(duration/2)*0.0343;
   Serial.println(distance);
   delay(5);
   if(distance<=20){
    digitalWrite(buzzer, HIGH);
    delay(distance*30);
    digitalWrite(buzzer, LOW);
    delay(distance*30);
   }

}