#define TRIGGER_PIN 18
#define ECHO_PIN 4
#define SPEED_SOUND 34300 //speed in cm/s

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(TRIGGER_PIN,OUTPUT);
  pinMode(ECHO_PIN,INPUT);
  digitalWrite(TRIGGER_PIN,LOW);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(TRIGGER_PIN,HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN,LOW);
  long time=pulseIn(ECHO_PIN,HIGH);
  float ans=((time/1e6)*SPEED_SOUND)/2;
  Serial.print("Distance Reading in cm: ");
  Serial.println(ans);
  delay(2000);
}