This is the RTC part of my code:

//Datalogger
#define SPIN 6  //Connect to the module Pin S, trigger to save files at low level
uint16_t i = 0;

//RTC
#include <DFRobot_DS1307.h>
//Note: #define updata_flag 0 //1 updata time,0 only show time
#define updata_flag 0  //1
DFRobot_DS1307 DS1307;
}

void setup() {

 //Datalogger

 Serial.begin(115200);
 delay(2000);  //To aviod data lost, delay a period of time to wait for the module to start
 pinMode(SPIN, OUTPUT);
 digitalWrite(SPIN, HIGH);

 //RTC

 //Serial.begin(115200);

 // Initialize sensor

 while (!(DS1307.begin())) {
   Serial.println("Communication with device failed, please check connection");
   delay(3000);
 }

 DS1307.start();

 DS1307.setSqwPinMode(DS1307.eSquareWave_1Hz);

 Serial.print("Time");
 Serial.print(",");
 Serial.print("Date");
 Serial.print(",");
 delay(100);

}

void loop() {

 Serial.print(DS1307.getTypeTime(DS1307.eHR));
 Serial.print(":");
 Serial.print(DS1307.getTypeTime(DS1307.eMIN));
 Serial.print(":");
 Serial.print(DS1307.getTypeTime(DS1307.eSEC));
 Serial.print(",");
 Serial.print(DS1307.getTypeTime(DS1307.eMTH));
 Serial.print("/");
 Serial.print(DS1307.getTypeTime(DS1307.eDATE));
 Serial.print("/");
 Serial.print(DS1307.getTypeTime(DS1307.eYR));
 Serial.print(",");
 delay(1000);
}