#include <LiquidCrystal.h>
#include <Keypad.h>
#include <Servo.h>
#include <stdio.h>
#include <stdlib.h>

/* Display */
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

/* Keypad setup */
const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
byte rowPins[KEYPAD_ROWS] = {5, 4, 3, 2};
byte colPins[KEYPAD_COLS] = {A3, A2, A1, A0};
char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
  {'1', '2', '3', '+'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '*'},
  {'.', '0', '=', '/'}
};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);

void setup(){
  Serial.begin(9600);
}
  
void loop(){
  char customKey = keypad.getKey();
  if (customKey) {
    lcd.clear();
    lcd.setCursor(0, 0); 
    lcd.print(customKey);
    data = customKey;
  }
}