#include <ESP32Time.h>

#define uS_TO_S_FACTOR 1000000ULL  /* Conversion factor for micro seconds to seconds */
#define TIME_TO_SLEEP  5        /* Time ESP32 will go to sleep (in seconds) */

ESP32Time rtc;


void wakeup_reason() {
  esp_sleep_wakeup_cause_t wakeup_reason;

    wakeup_reason = esp_sleep_get_wakeup_cause();
      switch (wakeup_reason)
        {
            case ESP_SLEEP_WAKEUP_EXT0 : Serial.println("Wakeup caused by external signal using RTC_IO"); break;
                case ESP_SLEEP_WAKEUP_EXT1 : Serial.println("Wakeup caused by external signal using RTC_CNTL"); break;
                    case ESP_SLEEP_WAKEUP_TIMER : Serial.println("Wakeup caused by timer"); break;
                        case ESP_SLEEP_WAKEUP_TOUCHPAD : Serial.println("Wakeup caused by touchpad"); break;
                            case ESP_SLEEP_WAKEUP_ULP : Serial.println("Wakeup caused by ULP program"); break;
                                default :
                                      Serial.printf("Wakeup was not caused by deep sleep: %d\n", wakeup_reason);
                                            rtc.setTime(30, 24, 15, 17, 1, 2021);  // 17th Jan 2021 15:24:30
                                                  //rtc.setTime(1609459200);  // 1st Jan 2021 00:00:00
                                                        //rtc.offset = 7200; // change offset value

                                                              break;
                                                                }
                                                                }

                                                                void setup() {
                                                                  Serial.begin(115200);

                                                                    wakeup_reason();

                                                                      Serial.println(rtc.getTime("%A, %B %d %Y %H:%M:%S"));   // (String) returns time with specified format

                                                                        esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);

                                                                          Serial.println("Going to sleep now");
                                                                            Serial.flush();
                                                                              esp_deep_sleep_start();
                                                                              }

                                                                              void loop() {
                                                                                
                                                                                }