#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // set the LCD address to 0x27 for a 16 chars and 2 line display

// Constants won't change
const int TRIG_PIN = 6; // Arduino pin connected to Ultrasonic Sensor's TRIG pin
const int ECHO_PIN = 7; // Arduino pin connected to Ultrasonic Sensor's ECHO pin
const int LED_PIN  = 13; // Arduino pin connected to LED's pin
const int DISTANCE_THRESHOLD = 5; // centimeters


// Variables will change:
float duration_us, distance_cm;

void setup() {
  Serial.begin(9600);       // Initialize serial port
  pinMode(TRIG_PIN, OUTPUT); // Set Arduino pin to output mode
  pinMode(ECHO_PIN, INPUT);  // Set Arduino pin to input mode
  pinMode(LED_PIN, OUTPUT);  // Set Arduino pin to output mode

  // Initialize the LCD
  lcd.init();         // initialize the lcd
  lcd.backlight();    // Turn on the LCD screen backlight
  lcd.print("Distance Sensor");
}

void loop() {
  // Generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Measure duration of pulse from ECHO pin
  duration_us = pulseIn(ECHO_PIN, HIGH);
  // Calculate the distance
  distance_cm = 0.017 * duration_us;

  // Control the LED based on distance
  if (distance_cm < DISTANCE_THRESHOLD)
    digitalWrite(LED_PIN, HIGH); // Turn on LED
  else
    digitalWrite(LED_PIN, LOW);  // Turn off LED

  // Print the value to Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance_cm);
  Serial.println(" cm");

  // Update the LCD display with the distance
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Distance(in cm)");
  lcd.setCursor(5,1);
  lcd.print(distance_cm);
  //lcd.print(" cm");

  delay(500);
}