2 Replies Latest reply on Oct 20, 2016 5:51 PM by pacrc_1517661

    Capacitive Liquid Level Sensor Kit - Sensor TX0

      I'm currently working with the Capacitive Liquid Level Sensor Kit . I think I have a good basic understanding of the basic principles behind the technology. On the sensor strips,  I note an additional strip called TX0. In the 2 sensor strip sensor there is a single TX0 strip and on the 12 sensor strip there are two TX0 strips.


      Looking at the TopDesign.cysch, I note a GPIO named Pin_TxGnd, which indicates this may act as GND. The pin is a Digital output with an initial setting of (Strong Drive)Low (0). On viewing with a scope the setting appears always to be zero. My initial thought is they act as a GND. CapSense essentially measures the Capacitance between the RX and TX strips. I guess, having the GND strips built into the sensor make the capacitance much more stable, rather than using RX strips alone.


      When I think TX, the word transmit comes to mind, and since the GPIO is a digital output, there is the possibility of a setting other than GND. I'm not sure what can be achieved with other settings though.

        • 1. Re: Capacitive Liquid Level Sensor Kit - Sensor TX0





          The sensor strips were designed to support CSX (mutual capacitive sensing) as well in addition to CSD (self capacitive sensing). The TX strip will be used in CSX sensing. Currently there are driven to ground to reduce the noise. You may set this pin to shield if needed.


          You may find more about CSX sensing in the following link.









          • 2. Re: Capacitive Liquid Level Sensor Kit - Sensor TX0

            CSX Mode looks very interesting. It could be used to filter out the effects of water droplets on the sensors. Condensation will be probably be more of a problem, since the entire surface may be covered.


            The board I am using has a PSOC 4200 series processor (CY8CKIT-042 PSOC 4 Pioneer KIT), so I believe it should be able to support CSX.


            In the Liquid Level Sensing Shield software, the 12 and 2 Sensor Version has the CapSense component which supports CSX. So I will look to investigate this further.