6 Replies Latest reply on Nov 21, 2019 6:19 PM by YuMa_1534086

    Regarding communication mode of CapSense Tuner

    YuMa_1534086

      Hello Cypress.

       

      I found a symptom that RawCount Noise changes by communication mode.

      At communication mode is Asynchronized, RawCount Noise is higher.

      At communication mode is Synchronized, RawCount Noise is lower.

      Please confirm below figure.

       

      Why does RawCount Noise change depending on communication mode?

       

      Below is test condition.

      ================================================

      Kit:                       CY8CKIT-145-40XX

      FW:                     CE210709_CapSense_Linear_Slider_and_Buttons

      VDDA/VDDD:     3.3V(Used MiniProg3)

      ================================================

       

       

       

      Best Regards.

      Yutaka Matsubara.

        • 1. Re: Regarding communication mode of CapSense Tuner
          RyanZ_36

          Dear Matsubara-san,

           

          According to datasheet of CapSense Component(https://www.cypress.com/file/492461/download ):

          "Asynchronized - When selected, the Tuner reads data asynchronously to sensor scanning. Because reading data by the CapSense Tuner and data processing happen asynchronously, the CapSense Tuner may read the updated data only partially. For example, the device updates only the first sensor data and the second sensor is not updated yet. At this moment, the CapSense Tuner is reading the data. As a result, the second sensor data is not processed. "

           

          So I think the phenomenon you met is caused by the "dirty data" read in the async mode. It is recommended to use sync mode to get the matched data when tuning CapSense.

           

          Best Regards,

          Ryan

          • 2. Re: Regarding communication mode of CapSense Tuner
            YuMa_1534086

            Ryan-san.

             

            Q1)

            In Asynchronized mode, there is I2C communication(Write/Read) even during scanning.

            So RawCount Noise in Asynchronized mode may be larger than Synchronized mode due to I2C communication(I2C frequency) itself.

            Is my understanding correct?

             

            Q2)

            If Q1 is correct, for application that PSoC and Host always communicate via I2C, is it better to use Asynchronized mode than Synchronized mode?

            Because Asynchronized mode is closer to actual application data than Synchronized mode in this case.

             

            Best Regards.

            Yutaka Matsubara

            • 3. Re: Regarding communication mode of CapSense Tuner
              RyanZ_36

              Matsubara-san,

               

              A1) Asynchronized means data Processing and Tuner running asynchronized. But with multiple sensors application, CapSense data should be transmitted to Tuner after all processing completed.

              A2) So...Synchronized mode is more closed to actual CapSense data.

               

              Best Regards,

              Ryan

              • 4. Re: Regarding communication mode of CapSense Tuner
                YuMa_1534086

                Ryan-san.

                 

                Below is description of CapSense Datasheet.

                ============================================================

                Asynchronized – When selected, the Tuner reads data asynchronously to sensor scanning.

                ============================================================

                 

                Asynchronized seems to read data regardless of sensor scanning and scan data processing.

                 

                I thought that RawCount noise at Asynchronized was increased by I2C communication at sensor scanning.

                Is my understanding correct?

                 

                If my understanding is wrong, could you please let us know the reason when RawCount noise at Asynchronized becomes bigger?

                 

                In tuner, it seems that RawCount noise increases as I2C frequency increases.

                Please confirm attached file.

                 

                Best Regards.

                Yutaka Matsubara

                • 5. Re: Regarding communication mode of CapSense Tuner
                  RyanZ_36

                  Matsubara-san,

                   

                  In Asynchronized mode, all register values can be read by Tuner GUI without hand shake mechanism. This mode will provide fastest data streaming from the DUT to report sensor data, but may not be reporting optimal performance numbers such as SNR.

                  Synchronized mode can make sure Tuner performs synchronized data read which guaranties consistency of the read data, or in other words that read raw counts, differences, baselines and statuses of all widgets are obtained from the same scan and processing cycle.

                   

                  Best Regards,

                  Ryan

                  • 6. Re: Regarding communication mode of CapSense Tuner
                    YuMa_1534086

                    Ryan-san.

                     

                    I do not know why RawCount noise changes due to I2C freq in Asynchronized.

                    Could you please let us know a detailed mechanism and condition that RawCount noise becomes bigger in Asynchronized?

                     

                    Best Regards.

                    Yutaka Matsubara