1 Reply Latest reply on Feb 3, 2018 3:42 AM by gani

    How to measure/read the capacitve value of a button?

    rodesposito_2800731

      I am developing an application for a touchpad where I use capacitive buttons in conjunction with the MIDI protocol to play some music notes. I would like to change the "velocity" parameter inside the library. This change must correspond to the pressure applied to the capacitive sensor touch. For example when you are playing the piano and you press the key harder. I'm not sure what function to use to do this. The parameter should vary with the variation of capacitance at the finger touch on the capacitive sensor. Any suggestions?

        • 1. Re: How to measure/read the capacitve value of a button?
          gani

          Hi,

           

          The idea of Cypress CapSense is to measure the parasitic capacitance of the sensor and converts it into a number. We call that number as raw counts. Based on the value of raw counts the parasitic capacitance can be estimated. So in your case in order to detect the pressure you should convert the pressure to capacitance. For that we recommend you to use a flexible dielectric so that when touched with more force the effective distance between the finger and overlay decreases and the raw counts increases. In this way you can detect pressure using CapSense. So please go through the PSoC 4 capSense design guide to design the application with a flexible overlay.

           

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

           

          Thanks and Regards

          Ganesh