8 Replies Latest reply on Feb 3, 2020 10:52 PM by AH_96

    Regarding an increase of CapSense RawCount at Power up.

    YuMa_1534086

      Hello Cypress.

       

      I confirmed that an increase of RawCount at Power up after Power-off(USB cable is removed, for about 5min).

      Please confirm PNG file.

       

      Is this the intended behavior?

      And could you please let us know why RawCount increases at Power-up?

      In this time, there is no temperature change.

       

      I used below 2 kits.

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

      CY8CKIT-042

      CY8CKIT-024

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

       

      I used attached FW.

      An increase of RawCount at Power-up occurred even if Fsw was lowered or Shield pin was disabled.

       

      Best Regards.

      Yutaka Matsubara.

        • 1. Re: Regarding an increase of CapSense RawCount at Power up.
          AH_96

          Hi YuMa_1534086

           

          I tried the code at my end with the same kits and did not observe this behavior. Could you please clarify the following?

           

          1. Are the kits being powered with the USB or is it external power supply? If it is being powered externally, is the power supply stable?

          2. Are there any grounded or metallic objects present near the sensors?

          3. During the test, if the device is powered down and connected back, does it restart from the lower point or continue increasing from where it was left?

          4. While sampling, if the device is reset, what is the behavior? Does it continue to increase?

          5. If the system is left for a long time, what is the impact? Does it continue to increase or does it settle down after some time?

           

          I realize that you have tried with a lower sense clock frequency, but even while testing, please make sure that the sensors are getting charged and discharged completely with 8 MHz sense clock frequency. Such high value is not suggested for final designs and must not be used.

           

          Thanks and regards

          Hari

          • 2. Re: Regarding an increase of CapSense RawCount at Power up.
            YuMa_1534086

            Hari-san.

             

            RawCount gradually increases for abut 5min from the beginning of power-on to PSoC.

            After that, RawCount increase stops.

             

            In this timing, RawCount increase does not occur even if toggling supply power to PSoC or resetting PSoC.

            So it is necessary to have a period when voltage is not completely supplied to PSoC to reproduce this issue.

             

            PSoC is powered from USB.

            So it needs times(5 -10 min) from USB cable removes, in order to make Power-off period.

            Because PSoC is automatically powered if USB cable is connected.

             

            Please connect USB cable to 042kit after Power-off(USB cable is removed, for about 5-10 min).

            Immediately after that, please monitor RawCount at CapSense tuner.

             

            Below is tuner setting.

            Number of samples needs to be increased because RawCount gradually increases.

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

            I2C Speed is 100kHz

            Number of samples is 10000(max setting)

            Synchronized mode

            042kit Vdd jumper setting is 3.3V

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

             

            An increase of RawCount at Power-up occurred even if Fsw was lowered(4000kHz, 2000kHz) or Shield pin was disabled.

            And there are not grounded or metallic objects present near the sensors.

             

            Best Regards.

            Yutaka Matsubara

            • 3. Re: Regarding an increase of CapSense RawCount at Power up.
              AH_96

              Hello Yutaka-san

               

              "PSoC is powered from USB.

              So it needs times(5 -10 min) from USB cable removes, in order to make Power-off period.

              Because PSoC is automatically powered if USB cable is connected."

              -> Please let me know how the PSoC is powered once the USB cable is removed. Is the test conducted by external power supply during this period?

               

              "Please connect USB cable to 042kit after Power-off(USB cable is removed, for about 5-10 min).

              Immediately after that, please monitor RawCount at CapSense tuner."

              -> Can you please clarify this statement? As I understand, the device must be powered down for 5-10 mins and then connected back to observe the raw counts and at this moment, there is an increases in raw-counts. However, this is the same as toggling power and it was stated that power toggle does not reproduce the issue. I tried the same with the tuner settings mentioned and did not observe the issue.

               

               

              Best regards

              Hari

              • 4. Re: Regarding an increase of CapSense RawCount at Power up.
                YuMa_1534086

                Hari-san.

                 

                Please confirm below.

                 

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

                Step1:     042kit does not connected USB cable.

                               So there is no supply voltage for PSoC4.(No VBUS, No external voltage)

                 

                Step2:      Wait 5-10min.

                   There is no supply voltage for PSoC4.(No VBUS, No external voltage)

                   Power off period becomes long.

                 

                Step3:   Connect USB cable to 042kit with 024kit.

                              Supply voltage for PSoC is powered from USB cable(VBUS).

                              There is no external voltage.

                 

                Step4:    Monitor CapSens tuner.

                              RawCount gradually increases for abut 5min.

                              And RawCount increase stops about 5min after connecting USB cable to 042kit with 024kit for the first time(Step3).

                              RawCount becomes stable.

                               RawCount increase does not occur even if resetting PSoC once RawCount becomes stable.

                               And RawCount increase does not occur even if USB cable is connected immediately after USB cable is removed(toggle supply voltage) once RawCount becomes stable.

                              Because Power off period is short.

                But RawCount increase occurs again when returning to Step1.

                 

                 

                This issue occurs at Power-on from Power-off period.

                But it does not occurs if Power-off period is short.(For example, toggle supply voltage).

                Long Power-off period(about 5-10 min) is required to reproduce this issue.

                So wait time after USB cable is removed is necessary(Step2)

                This issue may be caused by internal temperature of device.

                Because RawCount increase does not occur after some time from PSoC works.

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

                 

                 

                Best Regards.

                Yutaka Matsubara

                • 5. Re: Regarding an increase of CapSense RawCount at Power up.
                  YuMa_1534086

                  Hari-san.

                   

                  Can you reproduce this issue?

                   

                  If it is difficult to reproduce, I will close this discussion once.

                   

                  Best Regards.

                  Yutaka Matsubara

                  • 6. Re: Regarding an increase of CapSense RawCount at Power up.
                    AH_96

                    Hello YuMa_1534086

                     

                    i was able to reproduce the issue and I am looking into it. The issue is only reproducible when the 042 kit is connected to the proximity shield (I tried with the 040 kit and did not observe this).

                    We will investigate this issue and get back to you.

                     

                    Thank you,

                    Best Regards,

                    Hari

                    • 7. Re: Regarding an increase of CapSense RawCount at Power up.
                      YuMa_1534086

                      Hari-san.

                       

                      Can you update this discussion?

                       

                      Best Regards.

                      Yutaka Matsubara

                      • 8. Re: Regarding an increase of CapSense RawCount at Power up.
                        AH_96

                        Hi YuMa_1534086

                         

                        We are still investigating this issue. It seems to be caused due to increase in temperature only.

                         

                        I ran the code that measures the die temperature and monitored the raw counts and there seems to be a direct relation.

                        Kindly give me some time to find out the actual cause of this.

                         

                        I shall update as soon as this is done.

                         

                        Best regards,

                        Hari