6 Replies Latest reply on Dec 22, 2019 10:18 PM by MaMi_1205306

    FM24C16B : Communication speed setting

    MaMi_1205306

      Hi,

       

      FM24C16B supports 100kbps, 400kbps and 1Mbps.

      How do you recognize each mode?

       

      For example, confirm for the period when the clock is low.

      Or FRAM only confirms the clock edge, and FRAM can support any clock speed.

       

      There is a problem that data in FRAM disappears.
      It turns out that there are times when the clock speed of the I2C master changes.
      As a result, We would like to determine if there is a time when the I2C slave FRAM cannot respond.

       

      Regards,

        • 1. Re: FM24C16B : Communication speed setting
          PradiptaB_11

          Hi Masashi-san,

           

          The above mentioned FRAM part follows the standard I2C specifications. You can go through the I2C bus specifications user manual to know about each mode. (Link is given below)

          https://www.nxp.com/docs/en/user-guide/UM10204.pdf

           

          100 Kbps is standard mode, 400 Kbps is fast mode, 1 Mbps is fast mode plus. So basically the data transfer rate determines what mode you are operating in and it will depend on the I2C master as it will select a data transfer rate.

           

          Once a data transfer rate is selected and I2C peripheral is set up at the controller side you can begin the communication. If in the middle of the communication the transfer rate is changing then actually it is violating the I2C bus specifications and the communication cannot be guaranteed to be reliable. Kindly make sure the clock speed is same. Not only the FRAM part but any I2C slave device cannot guarantee reliability in such a case. Clock needs to be constant.

           

          Can you send us scope shots of the I2C communication with the FRAM. It will help us to understand if the Interface is set up correctly, and will give us idea about the data loss you are observing.

           

          Thanks,

          Pradipta.

          • 2. Re: FM24C16B : Communication speed setting
            MaMi_1205306

            Pradipta-san,

             

            Thank you for your support.

             

            I understand the I2C specification.

            I understand that each mode of I2C is up to 100kbps, up to 400kbps and 1Mbps, not a fixed value. Is that recognition correct?

             

            That recognition is correct,
            As an example, suppose two I2C masters and one I2C slave FRAM are connected on one I2C bus.

             

            I2C Master A accesses this FRAM at 250kbps.
            I2C Master B accesses this FRAM at 100kbps.

            Does FRAM recognize the mode at this time?
            If so, please tell me how.

            I think FRAM doesn't recognize the mode.

             

            Regards,

            Masashi

            • 3. Re: FM24C16B : Communication speed setting
              PradiptaB_11

              Masashi-san,

               

              The recognition is correct. I have only mentioned the maximum speed for each mode.

               

               

              The FRAM device will support I2C communication upto 1Mbps. There are necessary timing specifications to meet as per the datasheet ( according to the mode you are in). If the specifications are met then there will be no issues. I2C bus can have multi master mode. Kindly make sure you are configuring the masters correctly and applying the correct pull up resistance onto the I2C signals.

               

              You can provide us with the wave forms if you are having issues as the wave forms will help us understand better.

               

              Thanks,

              Pradipta.

              • 4. Re: FM24C16B : Communication speed setting
                MaMi_1205306

                Pradipta-san

                 

                We would like to know if this FRAM has settings for each mode(standard mode, fast mode, fast mode plus)?

                 

                I understand that this FRAM does not switch modes depending on the connected I2C master.
                Is that recognition correct?

                 

                Regards,

                Masashi

                • 5. Re: FM24C16B : Communication speed setting
                  PradiptaB_11

                  Masashi-san,

                   

                  The FRAM has no special settings for any mode. The recognition is correct.

                   

                  Regards,

                  Pradipta.

                  • 6. Re: FM24C16B : Communication speed setting
                    MaMi_1205306

                    Pradipta-san,

                     

                    Thank you for your support.

                    We understood this FRAM's operation.

                     

                    Regards,

                    Masashi