1 year, 9 months ago.

RTC DS1307 Issue

Hello I have a RTC DS1307 and I would like to set the real time and diplay it on an LCD. I have a program proposed by someone but it doesn't work : I have "Last R/W operation failed !" for the first one (I understand that the time isn't set), same for the second (gettime) and after all operations are "passed" but the time display is nul.

How to fix this issue and set the time ?

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);
                      // 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);

I think the initialization of the RTC doesn't work, so it doesn't start and I read 00:00:00 for the realTime.

posted by Théo Rostaing 29 Jun 2018

1 Answer

1 year, 9 months ago.


please check https://os.mbed.com/questions/61525/F401RE-I2C-library-does-not-work/

Maybe a still existing i2c lib problem?