1 Reply Latest reply on Aug 27, 2019 5:52 AM by BragadeeshV_41

    PSoC4 Capsense CSX method and Tuning

    TaKa_3997231

      I'm interested in using CSX method of capsense.

      So far I've used CSD method, but this is first time to use CSX.

      Then, I have questions.

       

      1. I can't understand principle and method of CSX. What kind of difference between CSX and CSD.

      I understand sigma-delta modulation of CSD, but cant' know the difference CSX and CSD.

       

      2. Regarding tuning of capsense(CSX), Is there any difference between CSX and CSD,

      saying , tuning method and parameters.

       

      First, I will try CSX method using CY8Ckit-042 with foil capacitance sensor made by myself.

      Can I use it?  I'm wondering if wiring to sensor could be suitable or not...

       

       

      相互容量式(CSX)の使用を考えています。

      これまで、自己容量式(CSD)は使ったことがありますが、CSXは初めてです。

       

      そこで質問が2つあります。

       

      1.CSXの測定方法の仕組み・回路がわかりません。CSDとの違いは何ですか?

      CSDはシグマデルタ変調ということは理解しているつもりです。

       

      2.Capsense(CSX)のチューニングについて、

      チューニング方法やパラメータにCSDと違いはありますか?

        • 1. Re: PSoC4 Capsense CSX method and Tuning
          BragadeeshV_41

          Hi TaKa_3997231,

           

          Please refer to the PSoC 4 CapSense design guide for information on CSX sensing method. Let us know if you have any specific doubts in CSX, we would be happy to help.

           

          https://www.cypress.com/file/46081/download

           

          In general, CSD measures the self capacitance between the sensor pad and ground. Whenever a finger is placed, Cf is added and this change in capacitance is measured by the CapSense IP to detect touch

          On the other hand, CSX measures the mutual capacitance between two electrodes (Tx and Rx).  Whenever a finger on a CSX sensor, the finger takes away some of the field lines going between the tx and rx electrodes. This reduces the field lines going between the tx and rx electrodes and therefore the mutual capacitance Cm reduces. This change in Cm is measured by the CapSense IP to detect touch.

           

          CSX is almost independent of the Cp of the electrodes and is most suitable when the Cp of the sensors are too high due to long trace lengths.

          CSX is ideal for touchpad as it supports multi touches unlike CSD which produces ghost effects.

           

          The hardware tuning parameters are different for CSD and CSX. Please refer to the CapSense design guide for help on CSX tuning. The software tuning parameters are the same for both these methods.

           

          We recommend you to use 4000S, 4100 S plus kits that has CSX based sensor patterns that is recommended by Cypress.

           

          We also have many code examples to show how to tune CSX sensors and the firmware flow:

          https://www.cypress.com/documentation/code-examples/ce210709-capsense-linear-slider-and-buttons

           

          Regards,

          Bragadeesh