//LCD I2C library:
#include <LiquidCrystal_I2C.h>
//DHT22 sensor library:
#include <DHT.h>
//LCD I2C address 0x27, 16 column and 2 rows!
LiquidCrystal_I2C lcd(0x27, 16, 2);

//Constants:
#define DHTPIN 2          //what pin we're connected to
#define DHTTYPE DHT22     //DHT 22  (AM2302)
#define light 8
DHT dht(DHTPIN, DHTTYPE); //Initialize DHT sensor for normal 16mhz Arduino

//Variables:
float H; //Humidity value
float T; //Temperature value

//Initialize LCD and DHT22 sensor:
void setup() {
  lcd.init();
  lcd.backlight();
  dht.begin();
  pinMode(light,OUTPUT);
  // Print some text in Serial Monitor
  Serial.begin(9600);
  Serial.println("DHT22 sensor with Arduino Uno R3!");
}

void loop() {
  delay(2000);
  // Read data and store it to variables hum and temp
  H = dht.readHumidity();
  T = dht.readTemperature();

  // Print temp and humidity values to serial monitor
  Serial.print("Humidity: ");
  Serial.print(H);
  Serial.println(" %; ");
  Serial.print("Temperature: ");
  Serial.print(T);
  Serial.println(" Celsius.\n");

  /* If humidity is higher than 70% & 
  temperature is higher than 30 degrees Celsius 
  then it will show on LCD „Too warm! Cool down!” */
  if (H >= 70.00 && T >= 30.00) {
    digitalWrite(light,HIGH);
    lcd.println("   Too warm!    ");
    lcd.setCursor(0, 1);
    lcd.println("   Cool down!   ");
    lcd.setCursor(0, 0);
    delay(2000);
    digitalWrite(light,LOW);
  } else {
    /* If humidity is lower than 70% & 
    temperature is lower than 30 degrees Celsius 
    then it will show on LCD „Temp. & hum. are in normal limits” */
    lcd.println("Temp. & hum. are");
    lcd.setCursor(0, 1);
    lcd.println("in normal limits");
    lcd.setCursor(0, 0);
  }

  /* If either humidity is lower than 70%, but 
  temperature is higher than 30 degrees Celsius, 
  then it will show on LCD „Be ware! Temp. too high” or
  humidity is higher than 70%, but 
  temperature is lower than 30 degrees Celsius, then
  it will show on LCD „Be ware! Hum. too high” */
  if (H < 70.00 && T >= 30.00) {
    lcd.println("Be ware!        ");
    lcd.setCursor(0, 1);
    lcd.println("Temp. too high! ");
    lcd.setCursor(0, 0);
  }
  if (H >= 70.00 && T < 30.00) {
    lcd.println("Be ware!" );
  }
}