MAX7219 plus RTC

// Program


#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>
#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
#define MAX_DEVICES 4
#define CLK_PIN   13
#define DATA_PIN  11
#define CS_PIN    10
MD_Parola P = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);


#include <Wire.h>
#include <DS3231.h>
DS3231 rtc;
RTCDateTime datumCas;
byte showtime;



void setup(void)
{
  Serial.begin(9600);

  P.begin();
  // Set the brightness of the led, 0= minimum, 15= maximum
  P.setIntensity(2);

  rtc.begin();
  rtc.setDateTime(__DATE__, __TIME__);
}

void loop(void)
{
  Serial.print("Datum a cas DS3231: ");
  Serial.print(datumCas.year);   Serial.print("-");
  Serial.print(datumCas.month);  Serial.print("-");
  Serial.print(datumCas.day);    Serial.print(" ");
  Serial.print(datumCas.hour);   Serial.print(":");
  Serial.print(datumCas.minute); Serial.print(":");
  Serial.print(datumCas.second); Serial.println("");


  //-----------------------------------------------------------
  //P.print(datumCas.hour && datumCas.minute && datumCas.second);
  delay(1000);
  datumCas = rtc.getDateTime();
  showtime = datumCas.second ;
  P.print(showtime);
  Serial.print("Kopie displeje na serial: ");
  Serial.print(showtime); Serial.println("");
  //-----------------------------------------------------------
}