//ESP32 DS3231 Deep Sleep Test

#include <Wire.h>
#define DS3231RTC_I2C_ADDRESS 0x68
#define I2C_SDA 21                                  //1
#define I2C_SCL 22

void clearAlarm1(){                                 //2    
  Wire.beginTransmission(DS3231RTC_I2C_ADDRESS);
  Wire.write(0x0F);                               
  Wire.write(B00000000);                          
  Wire.endTransmission();
}

void setup() {
  Wire.begin(I2C_SDA, I2C_SCL);                     //3
  clearAlarm1();                                    //4
  Serial.begin(115200);                             //5
  delay(1000);
  Serial.println("ESP32 woke up from deep sleep.");
  for(int i=3;i>=0;i--){
    Serial.print("Going back to sleep in ");
    Serial.println(i);
    delay(1000);
  }
  esp_sleep_enable_ext0_wakeup(GPIO_NUM_13,0);      //6
  esp_deep_sleep_start();                           //7
  Serial.println("This will never be printed.");    //8
}

void loop() {
  //This is not going to be called.
}