#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);
int but = 12;
int buttonState12 = 0;
int triggerPin = 19;  // Ultrasonic sensor trigger pin
int echoPin = 18;     // Ultrasonic sensor echo pin
int redLedPin = 2;   // Red LED pin
int greenLedPin = 4; // Green LED pin

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redLedPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  pinMode(but, INPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0); 
}
void loop() {
  buttonState12 = digitalRead(but);

  if (buttonState12 == HIGH) {
    lcd.backlight();
  } else {
    lcd.noBacklight(); 
  }

  long duration;
  float distance_cm;

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

  duration = pulseIn(echoPin, HIGH);

  
  distance_cm = duration * 0.034 / 2;

  
  lcd.setCursor(0, 0); 
  lcd.print("Distance: ");
  lcd.print(distance_cm);
  lcd.print("cm");

  
  if (distance_cm < 100) {
    digitalWrite(redLedPin, HIGH);
    lcd.setCursor(3, 1);
    lcd.print("     RED     ");
    digitalWrite(greenLedPin, LOW);  
  } else {
    digitalWrite(redLedPin, LOW);
    lcd.setCursor(3, 1);
    lcd.print("     GREEN     ");   
    digitalWrite(greenLedPin, HIGH); 
  }
}