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

// LCD configuration: Adjust the I2C address (0x27 is default, change if necessary)
LiquidCrystal_I2C lcd(0x27, 16, 2); // 0x27 or 0x3F depending on your module

// Pin Definitions
const int trigPin = 25;  // GPIO pin connected to the Trig pin of the HC-SR04
const int echoPin = 26;  // GPIO pin connected to the Echo pin of the HC-SR04
const int relayPin = 12; // GPIO pin connected to the IN pin of the relay module

// Distance Thresholds in centimeters
const float lowLevelThreshold = 10.0;  // Distance below which to turn on the relay
const float highLevelThreshold = 20.0; // Distance above which to turn off the relay

void setup() {
  // Initialize Serial Monitor at 115200 baud rate
  Serial.begin(115200);
  
  // Initialize the LCD
    lcd.init(); // initialize the lcd// Initialize the 16x2 LCD
  lcd.backlight();      // Turn on the LCD backlight
            // Clear the LCD screen
  
  

  // Pin setups
  pinMode(trigPin, OUTPUT);  // Set Trig pin as OUTPUT
  pinMode(echoPin, INPUT);   // Set Echo pin as INPUT
  pinMode(relayPin, OUTPUT); // Set Relay pin as OUTPUT
  digitalWrite(relayPin, LOW); // Ensure the relay is off initially
}

void loop() {
  long duration;
  float distance;

  // Trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the pulse from the Echo pin
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters
  distance = (duration * 0.0344) / 2.0;

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

  // Display distance on the LCD
  lcd.setCursor(0, 1);  // Set cursor to the second line for distance
  lcd.print("Dist: ");
  lcd.print(distance);
  lcd.print(" cm  ");   // Add extra spaces to overwrite old data

  // Control the relay based on the distance
  if (distance < lowLevelThreshold) {
    // Turn on the relay if distance is below the low threshold
    digitalWrite(relayPin, HIGH);
    lcd.setCursor(10, 1); // Update LCD to show relay status on the right
    lcd.print("ON ");
    Serial.println("Relay ON");
  } 
  else if (distance > highLevelThreshold) {
    // Turn off the relay if distance is above the high threshold
    digitalWrite(relayPin, LOW);
    lcd.setCursor(10, 1); // Update LCD to show relay status on the right
    lcd.print("OFF");
    Serial.println("Relay OFF");
  }

  // Wait before the next measurement
  delay(1000);
}