#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
const byte ROWS = 4;
const byte COLS = 4;
char hexaKeys[ROWS][COLS] = {
{'1', '2', '3', 'A'},
{'4', '5', '6', 'B'},
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};
LiquidCrystal_I2C lcd(0x27,16,2);
byte rowPins[ROWS] = {11, 10, 9, 8};
byte colPins[COLS] = {7, 6, 5, 4};
byte pinRelay = 2;
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);
void setup() {
  lcd.begin(16,2);
  lcd.clear();
  lcd.backlight();
  pinMode(pinRelay, OUTPUT);
}
int count = 0;
void loop() {
  char customKey = customKeypad.getKey();
  if (customKey) {
    if (customKey!='C') {
      lcd.print(customKey);
      count++;
    }
    switch(customKey){
      case '*':
        digitalWrite(pinRelay,HIGH);
      break;
      case '#':
        digitalWrite(pinRelay,LOW);
      break;
      case 'C':
        if (count>0) {
          count--;
        }
        lcd.setCursor(count,0);
        lcd.print(' ');
        lcd.setCursor(count,0);
      break;
    }
    if (count>=16) {
      count=0;
      lcd.clear();
      lcd.setCursor(0,0);
    }
  }
}