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

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define p_pin A0
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

byte colPins[COLS] = { 5, 4, 3, 2 }; 
byte rowPins[ROWS] = { 9, 8, 7, 6 }; 

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

void setup() {
  pinMode(p_pin, INPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Press a Key:");
  delay(2000);
}

void loop() {
 
  int contrastValue = analogRead(p_pin);
  int contrast = map(contrastValue, 0, 1023, 0, 255);
  // lcd.command(0x21);           
  // lcd.command(0x80 | contrast); 
  // lcd.command(0x20); 

  char key = keypad.getKey();

  if (key) {
    lcd.setCursor(0,1);
    lcd.print("key: ");
    lcd.print(key);
    // Serial.println(key);
  }

  

}