#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // set the LCD address to 0x27 for a 16 chars and 2 line display
/*
 * keypad example.
 */
 
// analog pin connected to keypad
#define KEYPAD_PIN 0
 
// milliseconds to wait, to make sure key is pressed
#define TIME_TO_WAIT 50

void setup()
{
  lcd.init();                      // initialize the lcd
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(1, 0);
  lcd.print("Hello, world!");
  lcd.setCursor(0, 1);
  lcd.print("LiquidCrystalI2C");
  Serial.begin(9600);
}

void loop()
{
    // reading once
    int r1 = analogRead(KEYPAD_PIN) / 10 * 10;
    // waiting
    delay(TIME_TO_WAIT);
    // reading 2nd time - to make sure key is pressed for at least TIME_TO_WAIT milliseconds
    int r2 = analogRead(KEYPAD_PIN) / 10 * 10;
    if (r1 == r2) {
        switch (r1) {
        case 350: lcd.setCursor(0, 1); lcd.println(" 0 "); break;
        case 270: lcd.setCursor(0, 1); lcd.println(" 1 "); break;
        case 360: lcd.setCursor(0, 1); lcd.println(" 2 "); break;
        case 120: lcd.setCursor(0, 1); lcd.println(" 3 "); break;
        case 210: lcd.setCursor(0, 1); lcd.println(" 4 "); break;
        case 330: lcd.setCursor(0, 1); lcd.println(" 5 "); break;
        case 0  : lcd.setCursor(0, 1); lcd.println(" 6 "); break;
        case 240: lcd.setCursor(0, 1); lcd.println("7"); break;
        case 340: lcd.setCursor(0, 1); lcd.println("8"); break;
        case 50 : lcd.setCursor(0, 1); lcd.println("9"); break;
        case 250: lcd.setCursor(0, 1); lcd.println("*"); break;
        case 80 : lcd.setCursor(0, 1); lcd.println("#"); break;
        }
    }
}