1 Reply Latest reply on Jan 8, 2018 10:55 PM by rzzh

    Difference in Raw Count and Baseline




      For our custom design board, we are using CY8C28545 PSoc1 device.  This board have 6 capsense button, operated using CSD user module. We use Bridge Control Panel to observe the different parameters.


      Soon after we power ON board, in absence of finger touch, Baseline values are very close to RawCount values of the sensor. If any negative spike occur baseline drop to low value and gradually recover to normal raw count value. But after some time, because of new negative spike   Baseline value drop to low count, and remain stuck at that level though Diffcount values are positive. I have attached graph plot of RawCount values and Baseline.


      We have set,

      Negative Noise Threshold - 10

      Low Baseline Reset - 50



      So, few question in this regard as below.


      1> What is the reason for Baseline not to returning to average RawCount value ? How to overcome this issue.


      2> Also, during normal operation, If negative noise spike occur when finger is present above the sensor, this cause the sensor to turn OFF as Diffcount value drop to low value. Is there any parameter to set Debounce effect, for Rawcounts going on negative side.


      Please clarify,





        • 1. Re: Difference in Raw Count and Baseline

          Hi Vishal,


          Suggest to find the root cause. Please double-check Cmod, Rb, Series resistors on sensors are in recommended arrangement, double-check VDD voltage waveform and XRES waveform are stable.

          The Debounce parameter in CSD is used for finger touch report, not for negative spike.

          Recommend to disable sensor-autoreset, increase Low Baseline Reset to 100, 150, 200, 255 step by step to verify if it can work.

          In addition,  you can add IIR filter manually to filter the spike.

          At last, recommend to migrate your design to PSoC4. PSoC4 CapSense is more flexible and easier to tune. The performance will be better either.