3 Replies Latest reply on Dec 9, 2014 9:25 AM by Irakandjii

    Wire.h - I can read I2C but not write.  Anyone know how to get writes operating?


      Hi all


      I have read a number of posts on I2C but did not see a specific look at  " int Wire.write(uint8_t)" a method accessed by the intel Wire.h header .  This method does not seem to be working as required.


      I decided to use a Real Time Clock as my test device since they are pretty standard.

      Using the Arduino / Edison I can read the DS3231 rtc, but not write to it whilst using the Sketch below.

      The same Sketch works "perfectly" on a MEGA 2560.


      The Arduino IDE file is attached below .


      Excerpt from attached Sketch


      void set3231Year()


        // Use Yxx where xx is a 2 digit year

        year = (uint8_t) ((Serial.read() - 48) *10 + (Serial.read() - 48));  //

        Serial.print("The new year will be : ");  Serial.println(year);

        Wire.beginTransmission(DS3231_I2C_ADDRESS);  // Open the RTC

      Serial.print(Wire.write(DS3231_year));       // write the address pointer to the device in this case 0x06 = DS3231_year reports 1 byte written

        Serial.println(" addresss uint8_ts were written.");


        Serial.println( Wire.write(decToBcd(year)));  // Write the byte of data to the register at 0x06





      after execution of this method, the RTC remains unchanged