Das Real Time Clock Modul DS3231

#include <LiquidCrystal.h>

#include <Wire.h>
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
#define DS3231_I2C_ADDRESS 0x68
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
  return( (val/10*16) + (val%10) );
}
// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
  return( (val/16*10) + (val%16) );
}
void setup()
{
  Wire.begin();
  Serial.begin(9600);
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Datum:");
  }
void setDS3231time(byte second, byte minute, byte hour, byte dayOfWeek, byte
dayOfMonth, byte month, byte year)
{
  // sets time and date data to DS3231
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); // set next input to start at the seconds register
  Wire.write(decToBcd(second)); // set seconds
  Wire.write(decToBcd(minute)); // set minutes
  Wire.write(decToBcd(hour)); // set hours
  Wire.write(decToBcd(dayOfWeek)); // set day of week (1=Sunday, 7=Saturday)
  Wire.write(decToBcd(dayOfMonth)); // set date (1 to 31)
  Wire.write(decToBcd(month)); // set month
  Wire.write(decToBcd(year)); // set year (0 to 99)
  Wire.endTransmission();
}
void readDS3231time(byte *second,
byte *minute,
byte *hour,
byte *dayOfWeek,
byte *dayOfMonth,
byte *month,
byte *year)
{
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); // set DS3231 register pointer to 00h
  Wire.endTransmission();
  Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
  // request seven bytes of data from DS3231 starting from register 00h
  *second = bcdToDec(Wire.read() & 0x7f);
  *minute = bcdToDec(Wire.read());
  *hour = bcdToDec(Wire.read() & 0x3f);
  *dayOfWeek = bcdToDec(Wire.read());
  *dayOfMonth = bcdToDec(Wire.read());
  *month = bcdToDec(Wire.read());
  *year = bcdToDec(Wire.read());
}
void displayTime()
{
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
  // retrieve data from DS3231
  readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month,
  &year);
  // send it to the serial monitor
  Serial.print(hour, DEC);
  // convert the byte variable to a decimal number when displayed
  Serial.print(":");
  if (minute<10)
  {
    Serial.print("0");
  }
  Serial.print(minute, DEC);
  Serial.print(":");
  if (second<10)
  {
    Serial.print("0");
  }
  Serial.print(second, DEC);
  Serial.print(" ");
  Serial.print(dayOfMonth, DEC);
  Serial.print("/");
  Serial.print(month, DEC);
  Serial.print("/");
  Serial.print(year, DEC);
  Serial.print(" Day of week: ");
  switch(dayOfWeek){
  case 1:
    Serial.println("Sunday");
    break;
  case 2:
    Serial.println("Monday");
    break;
  case 3:
    Serial.println("Tuesday");
    break;
  case 4:
    Serial.println("Wednesday");
    break;
  case 5:
    Serial.println("Thursday");
    break;
  case 6:
    Serial.println("Friday");
    break;
  case 7:
    Serial.println("Saturday");
    break;
  }
  {
    lcd.setCursor(7, 0);
    lcd.print(dayOfMonth);
    lcd.print(":");
    lcd.print(month);
    lcd.print(":");
    lcd.print(year);
    
    lcd.setCursor(0, 1);
  lcd.print("Uhr: ");
  lcd.print(hour, DEC);
  lcd.print(":");
  if (minute<10)
  {
    lcd.print("0");
  }
  lcd.print(minute, DEC);
  lcd.print(":");
  if (second<10)
  {
    lcd.print("0");
  }
  lcd.print(second, DEC);
  // set up the LCD's number of columns and rows:
  //lcd.begin(0, 1);
  // Print a message to the LCD.
  }
}
void loop()
{
  displayTime(); // display the real-time clock data on the Serial Monitor,
  delay(1000); // every second

}

#include <RTClib.h>
#include <LiquidCrystal_I2C.h>

//Initialisiere RTC
RTC_DS3231 rtc;

// Initialisiere das LCD-Display
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  // Initialisiere das LCD-Display
  lcd.init();

  // Aktiviere das Backlight des LCD-Displays
  lcd.backlight();

  // Überprüfe, ob die RTC korrekt funktioniert
  if (! rtc.begin()) {
    lcd.print("RTC konnte nicht gefunden werden!");
    while (1);
  }

  // Setze die Zeit der RTC
  rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
}

void loop() {
  // Lese die aktuelle Zeit von der RTC aus
  DateTime now = rtc.now();

  // Formatiere Datum und Uhrzeit
  char buffer[20];
  sprintf(buffer, "%02d.%02d.%04d", now.day(), now.month(), now.year());
  String dateStr = String(buffer);

  sprintf(buffer, "%02d:%02d:%02d", now.hour(), now.minute(), now.second());
  String timeStr = String(buffer);

  // Schreibe Datum und Uhrzeit auf das LCD-Display
  lcd.setCursor(0, 0);
  lcd.print(dateStr);
  lcd.setCursor(0, 1);
  lcd.print(timeStr);

  // Warte eine Sekunde und aktualisiere das Display
  delay(1000);
  lcd.clear();
}

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

RTC_DS3231 rtc;

LiquidCrystal_I2C lcd(0x27, 16, 4);

void setup() {
  Wire.begin();
  rtc.begin();
  lcd.init();
  lcd.backlight();
  rtc.adjust(DateTime(__DATE__, __TIME__));
}

void loop() {
  DateTime now = rtc.now();
  
  float temperature = rtc.getTemperature();
  
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Date: ");
  lcd.print(now.day(), DEC);
  lcd.print('/');
  lcd.print(now.month(), DEC);
  lcd.print('/');
  lcd.print(now.year(), DEC);
  lcd.setCursor(0,1);
  lcd.print("Time: ");
  lcd.print(now.hour(), DEC);
  lcd.print(':');
  lcd.print(now.minute(), DEC);
  lcd.print(':');
  lcd.print(now.second(), DEC);
  lcd.setCursor(0,2);
  lcd.print("Temp: ");
  lcd.print(temperature, 2);
  lcd.print("C");
  
  delay(1000);
}