#include <Wire.h>
#include "LiquidCrystal_I2C.h"
LiquidCrystal_I2C lcd(0x27, 16, 2);

#define TRIG 25
#define ECHO 26
#define RED_PIN 18
#define GREEN_PIN 5
long duration, distance;
void setup() {
  // put your setup code here, to run once:
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  lcd.begin();
  lcd.backlight();
  lcd.home();

  lcd.print("Check Distance");
  lcd.setCursor(0, 1);
  lcd.print("Ready!");
  delay(2000);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(TRIG, LOW);
  delayMicroseconds(5);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  duration = pulseIn(ECHO, HIGH);
  distance = duration * 0.034 / 2;
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" cm. ");
  lcd.setCursor(0, 1);
  if (distance >= 15) {
    digitalWrite(GREEN_PIN, HIGH);
    digitalWrite(RED_PIN, LOW);
    lcd.print("Safe!");
  } else {
    digitalWrite(GREEN_PIN, LOW);
    digitalWrite(RED_PIN, HIGH);
    lcd.print("STOP! ");
  }
  delay(500);
}