//Date: 03.11.2025
//Name: Rajaram Parida
//Redg: 2241016203
//Section: 28
//Exp. No.: 4

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

#define TRIG_PIN 2
#define ECHO_PIN 3

#define LED1 4
#define LED2 5
#define LED3 6
#define LED4 7

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);

  lcd.begin(16, 2);
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Distance:");

  Serial.begin(9600);
}

void loop() {
  long duration;
  float distance;

  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;

  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm     ");

  digitalWrite(LED1, distance < 100);
  digitalWrite(LED2, distance < 75);
  digitalWrite(LED3, distance < 50);
  digitalWrite(LED4, distance < 25);

  delay(200);
}