int pingPin = 27;
int echoPin = 26;
int buzz    = 25;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(buzz, OUTPUT);
  pinMode(pingPin,OUTPUT);
  pinMode(echoPin,INPUT);
  }

void loop() {
  // put your main code here, to run repeatedly:
  //delay(10); // this speeds up the simulation
  long duration,inches,cm;
  digitalWrite(pingPin,LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin,HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPin,LOW);

  duration = pulseIn(echoPin,HIGH);
  inches   = microsecondsToInches(duration);
  cm       = microsecondsToCentimeters(duration);
  if(cm>100){digitalWrite(buzz,HIGH);}
  else{digitalWrite(buzz,LOW);}
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  delay(100);
}


long microsecondsToInches(long microseconds) {
   return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds) {
   return microseconds / 29 / 2;
}