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

// Define pin connections for ultrasonic sensor
const int trigPin = 10;
const int echoPin = 9;

// Define LEDs
const int redLed = 12;
const int yellowLed = 13;

// Initialize LCD
LiquidCrystal_I2C lcd1(0x27, 16, 2);  // LCD1 address and size
LiquidCrystal_I2C lcd2(0x3F, 16, 2);  // LCD2 address and size (might vary depending on your I2C address)

void setup() {
  // Start serial communication for debugging
  Serial.begin(9600);

  // Initialize ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Initialize LED pins
  pinMode(redLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);

  // Initialize LCD displays
  lcd1.begin(16, 2);
  lcd2.begin(16, 2);

  lcd1.print("Distance Sensor");
  lcd2.print("Waiting...");
  delay(2000);  // Delay for initialization
}

void loop() {
  // Trigger the ultrasonic sensor to send out a pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the time it takes for the pulse to return
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters
  long distance = duration * 0.034 / 2;  // Speed of sound is 0.034 cm/us, divided by 2 for round-trip

  // Display distance on both LCDs
  lcd1.clear();
  lcd1.setCursor(0, 0);
  lcd1.print("Distance:");

  lcd2.clear();
  lcd2.setCursor(0, 0);
  lcd2.print("Dist: ");
  lcd2.print(distance);
  lcd2.print(" cm");

  // LED control based on distance
  if (distance < 10) {
    // If the object is too close (less than 10 cm)
    digitalWrite(redLed, HIGH);   // Turn on red LED
    digitalWrite(yellowLed, LOW); // Turn off yellow LED
  } else if (distance >= 10 && distance < 50) {
    // If the object is at a safe distance (between 10 cm and 50 cm)
    digitalWrite(redLed, LOW);    // Turn off red LED
    digitalWrite(yellowLed, HIGH); // Turn on yellow LED
  } else {
    // If the object is far enough
    digitalWrite(redLed, LOW);    // Turn off red LED
    digitalWrite(yellowLed, LOW); // Turn off yellow LED
  }

  // Delay before next measurement
  delay(500);
}