#include <Keypad.h>
#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
}

void loop() {
  lcd.setCursor(0, 0); //cell,row
  lcd.print("Key =");
  char key = keypad.getKey();
  lcd.setCursor(6, 0); //cell,row

  if (key != NO_KEY) {
    //Serial.print(key);
    //Serial.print(" ");
    //lcd.setCursor(key,0);
    lcd.print(key);
    delay(1000);
    //lcd.clear();
  }
}