#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
char first, second, oper, equal;
//ekran
#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2
//klawa
const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { 1, '2', '3', '*' },
  { '4', '5', '6', '/' },
  { '7', '8', '9', '+' },
  { '.', '0', '=', '-' }
};
//keypad pin
uint8_t colPins[COLS] = { 5, 4, 3, 2 };
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 };
//Deklaracje
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
//fabryczne ustawieniac
void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
}
//powatarzac
void loop() {
  char key = keypad.getKey();
  

  if (key != NO_KEY) {
    
    Serial.println(key);
    lcd.print(key);
  }
}