include the mbed library with this snippet

// show how the DS1307 class works
  #include "ds1307.h"
  #include "mbed.h"
 
  Serial pc(USBTX, USBRX); // tx, rx  for debug and usb pc comunications
 
  DS1307 my1307(D14,D15); // start DS1307 class and give it pins for connections of the DS1307 device
 
  int sec = 0;
  int min = 0;
  int hours = 0;
  int day = 0;
  int date = 0;
  int month = 0;
  int year = 0;
 
  void test_rw(int test) {
      if (test == 0) pc.printf("Last R/W operaion passed!\n\r");
      else pc.printf("Last R/W operation failed!\n\r");
  }
 
  int main() {
      int junk = 0;
 
      sec = 24;       // 24 seconds
      min = 13;       // 13 min
      hours = 13;     // 1 pm
      day = 4;        // wednesday
      date = 20;      // June 20
      month = 6;
      year = 12;      // 2012
                      // set time to these values on the ds1307 connected device
 
      test_rw(my1307.settime( sec, min, hours, day, date, month, year));
      pc.printf("seconds set are %.2D \n\r",sec);
      pc.printf("min set are %.2D \n\r",min);
      pc.printf("hour set are %.2D \n\r",hours);
      pc.printf("day set are %.2D \n\r",day);
      pc.printf("date set are %.2D \n\r",date);
     pc.printf("month set are %.2D \n\r",month);
      pc.printf("year set are %.2D \n\r",year);
      wait(3);
                      // now read the time of the DS1307 device and see what time it is
                      // note that because of the 3 second wait this time should be 3 seconds past what it was set to earlier
 
     test_rw(my1307.gettime( &sec, &min, &hours, &day, &date, &month, &year));
      pc.printf("seconds read are %.2D \n\r",sec);
      pc.printf("min read are %.2D \n\r",min);
      pc.printf("hour read are %.2D \n\r",hours);
      pc.printf("day read are %.2D \n\r",day);
      pc.printf("date read are %.2D \n\r",date);
      pc.printf("month read are %.2D \n\r",month);
     pc.printf("year read are %.2D \n\r",year);
 
      junk = 0x39;                            // just a junk value do read and write test to DS1307 ram
      test_rw(my1307.write( 0x20, junk));     // this should write the value of junk to register 0x20 (a ram location) in the ds1307.
      pc.printf("Value written to register 0x20 %.2X \n\r",junk);
      junk = 0;                               // clear junk to show that when the register is read from the correct value is obtained
      test_rw(my1307.read( 0x20, &junk));     // this should read register 0x20
     pc.printf("Value read from register 0x20 %.2X \n\r",junk);
  }