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

LiquidCrystal_I2C lcd(0x27, 16, 2);

unsigned long lastUpdateMs = 0;
unsigned long seconds = 0;

void setup() {
  Wire.begin();
  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Czas dzialania:");
  lcd.setCursor(0, 1);
  lcd.print("0 s");
}

void loop() {
  unsigned long now = millis();

  if (now - lastUpdateMs >= 1000) {
    lastUpdateMs += 1000;     
    seconds++;

    lcd.setCursor(0, 1);
    lcd.print("                ");
    lcd.setCursor(0, 1);
    lcd.print(seconds);
    lcd.print(" s");
  }


}