#include <STM32RTC.h>

/* Get the RTC object */
STM32RTC& rtc = STM32RTC::getInstance();

void setup() {
  Serial.begin(9600);
    while (!Serial); // Wait for Serial monitor

      // Select RTC clock source BEFORE rtc.begin()
        rtc.setClockSource(STM32RTC::LSE_CLOCK);  // Use external 32.768 kHz crystal (better accuracy)
          rtc.begin();  // Start RTC in 24H format

            // If RTC is not already set (first power-up), set it to compile time
              if (!rtc.isTimeSet()) {
                  // Parse __DATE__ and __TIME__ (compile-time macros)
                      const char monthNames[12][4] = {"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};
                          char compileDate[] = __DATE__;
                              char compileTime[] = __TIME__;

                                  int day, year, hour, minute, second;
                                      char monthStr[4];
                                          sscanf(compileDate, "%s %d %d", monthStr, &day, &year);
                                              sscanf(compileTime, "%d:%d:%d", &hour, &minute, &second);

                                                  int month = 0;
                                                      for (int i = 0; i < 12; i++) {
                                                            if (strncmp(monthStr, monthNames[i], 3) == 0) {
                                                                    month = i + 1;
                                                                            break;
                                                                                  }
                                                                                      }

                                                                                          rtc.setTime(hour, minute, second);
                                                                                              rtc.setDate(1, day, month, year - 2000);  // Weekday is dummy (1 = Monday)
                                                                                                }

                                                                                                  Serial.println("RTC Initialized");
                                                                                                  }

                                                                                                  void loop() {
                                                                                                    // Read current date and time
                                                                                                      byte day = rtc.getDay();
                                                                                                        byte month = rtc.getMonth();
                                                                                                          byte year = rtc.getYear();
                                                                                                            byte hour = rtc.getHours();
                                                                                                              byte minute = rtc.getMinutes();
                                                                                                                byte second = rtc.getSeconds();

                                                                                                                  // Print date and time
                                                                                                                    Serial.print(day < 10 ? "0" : ""); Serial.print(day);
                                                                                                                      Serial.print("/");
                                                                                                                        Serial.print(month < 10 ? "0" : ""); Serial.print(month);
                                                                                                                          Serial.print("/");
                                                                                                                            Serial.print(year);
                                                                                                                              Serial.print(" ");

                                                                                                                                Serial.print(hour < 10 ? "0" : ""); Serial.print(hour);
                                                                                                                                  Serial.print(":");
                                                                                                                                    Serial.print(minute < 10 ? "0" : ""); Serial.print(minute);
                                                                                                                                      Serial.print(":");
                                                                                                                                        Serial.print(second < 10 ? "0" : ""); Serial.println(second);

                                                                                                                                          delay(1000);
                                                                                                                                          }