1 2 Previous Next 16 Replies Latest reply on Feb 5, 2020 11:01 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
          RuzheZ_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
              RuzheZ_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
                  RuzheZ_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

                    • 7. Re: Regarding communication mode of CapSense Tuner
                      RuzheZ_36

                      Matsubara-san,

                       

                      Apologized sincerely for the late reply.

                      In Asynchronized mode, the Tuner reads data asynchronously with sensor scanning and data processing. Due to this, data coherency may be corrupted. So, the Tuner may read only partially updated sensor data.

                       

                      Thanks,

                      Ryan

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

                        Ryan-san.

                         

                        >>> Due to this, data coherency may be corrupted. So, the Tuner may read only partially updated sensor data.

                        If tuner reads rawcount during updating, rawcount shifted about 1 byte is monitored.

                        For example, RawCount LSB was updated, but MSB was not updated yet(MSB is previous data).

                         

                        When data coherency is corrupted, I think that rawcount becomes waveform like spike noise(about 255).

                        Because the timing when tuner reads rawcount is not always the timing that data coherency is corrupted.

                        In rare case, tuner reads rawcount during updating.

                        So spike noise occurs in rawcount waveform at Asynchronized mode.

                         

                        Spike noise occurs when rawcount is at the boundary of whether MSB 0bit or LSB 7bit is set or not.

                         

                        Below link is discussions about this case.

                        => https://community.cypress.com/thread/50528

                         

                         

                        But this noise I am asking is not spike noise.

                        Rawcount noise increases overall at Asynchronized mode.

                        And amount of noise increase is much smaller than 1 byte.

                         

                        Therefore, I think that this noise increase has nothing to do with data coherency.

                        I think that there is another reason for the increase in noise.

                         

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

                        Because rawcount noise increases as I2C frequency increases.

                         

                        And rawcount range I captured is not at the boundary that spike noise occurs by data coherency corruption.

                         

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

                         

                        Best Regards.

                        Yutaka Matsubara

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

                          Ryan-san.

                           

                          Can you update this discussion?

                           

                          Best Regards.

                          Yutaka Matsubara

                          • 10. Re: Regarding communication mode of CapSense Tuner
                            RuzheZ_36

                            Matsubara-san,

                             

                            Apologized for the late. Have you tried with using the KitProg2/3 on the kit for Tuner? Can this issue be reproduced?  I tested the same fw on KIT-145. It works well. I can't see so large noise with I2C speed changing...

                             

                            Best Regards,

                            Ryan

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

                              Ryan-san.

                               

                              I used MiniProg3.

                              CY8CKIT-145-40XX and MiniProg3 were connected by jumper.

                              VDDA/VDDD setting is 3.3V(Not 5V).

                               

                              Best Regards.

                              Yutaka Matsubara

                              • 12. Re: Regarding communication mode of CapSense Tuner
                                RuzheZ_36

                                Matsubara-san,

                                 

                                I used MP3+145, 3.3V, to run the tuner. Red is Async mode, Green is sync mode. It doesn't have too much difference...

                                Software: PSoC Creator 4.2(build 641), CapSense V5.0

                                Hardware: MiniProg-3, KIT-145(Rev.12)

                                 

                                tempsnip.png

                                MP3_145_I2C.jpg

                                • 13. Re: Regarding communication mode of CapSense Tuner
                                  RuzheZ_36

                                  All CapSense filters are not enabled in the project.

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

                                    Ryan-san.

                                     

                                    I reproduced this issue by using your FW.

                                     

                                    - Have AC adaptor and external display monitor been removed from your laptop PC?

                                    Symptoms may be difficult to observe due to external noise.

                                     

                                    - If I2C speed is changed to 1MHz, can this symptoms be confirmed?

                                    The faster I2C speed is, the easier it is to observe this symptom.

                                     

                                    Best Regards.

                                    Yutaka Matsubara

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