#include <SoftwareSerial.h>
#include <LiquidCrystal_I2C.h>
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT22
char key = '0';


LiquidCrystal_I2C lcd(0x27, 20, 4);
DHT dht(DHTPIN, DHTTYPE);
void setup()
{
  Serial.begin(9600);
  lcd.init();
  dht.begin();
  Serial.println("Hello Arduino\n");
}
void loop(){
if (Serial.available() > 0) {
  key = Serial.read(); 
  Serial.print("key : ");
  Serial.println(key); 
  }
if (key == '0'){
  lcd.clear(); 
  lcd.noBacklight();
  }
else if (key == '1'){
  lcd.clear(); 
  lcd.backlight();
  op();
  }
}
void op(){
  float humi  = dht.readHumidity();
  float tempC = dht.readTemperature();

  lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Temperature : ");
    lcd.print(tempC);
    lcd.print("C");

    lcd.setCursor(2, 2);
    lcd.print("Humidity : ");
    lcd.print(humi);
    lcd.print("%");
  }