#include <LiquidCrystal.h>

const int rs = 5, en = 18, d4 = 19, d5 = 21, d6 = 22, d7 = 23;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

const int trigPin = 25;
const int echoPin = 26;
const int led = 2;
//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;
float distanceInch;

void setup() 
{
  Serial.begin(115200); // Starts the serial communication
  lcd.begin(16,2);
  //lcd.setCursor(0,0);
  //lcd.print("ultrasonic");
  //lcd.setCursor(0,1);
  //lcd.print("Interface in esp-32");
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); 
  pinMode(led, OUTPUT);
  delay(3000);
  lcd.clear();
}

void loop() {

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  //Serial.println("Duration:");
  //Serial.println(duration); 
  distanceCm = duration * SOUND_SPEED/2;
  distanceInch = distanceCm * CM_TO_INCH;
  digitalWrite(led,LOW);
  if (distanceCm<30)
  {
    digitalWrite(led,HIGH);
  }
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  Serial.print("Distance (inch): ");
  Serial.println(distanceInch);
  lcd.setCursor(0,0);
  lcd.print("cm: ");
  lcd.println(distanceCm);
  lcd.setCursor(1,1);
  lcd.print("inch: ");
  lcd.println(distanceInch);
  delay(1000);
}