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

LiquidCrystal_I2C lcd(0x27, 16, 2);

byte switchPort[] = {1<<0, 1<<1, 1<<2, 1<<3};
byte lcdX[] = {0, 15, 0, 15};
byte lcdY[] = {0, 0, 1, 1};

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

  DDRB &= ~(0b00001111);
  PORTB |= 0b00001111;
}

void loop() {
  for (int i = 0; i < 4; i++) {
    lcd.setCursor(lcdX[i], lcdY[i]);
    
    if ((PINB & switchPort[i]) == 0) {
      lcd.print("X");
      Serial.println("X");
    } else {
      lcd.print("0");
      Serial.println("0");
    }
  }
}