1 Reply Latest reply on Dec 26, 2016 1:08 AM by gani

    CapSense v2.50

    tfontaine_1975986

      I am using Chip: CY8C4245 LQI-483 and Program: PSoC Creator 4.

         

      I have a custom designed board with 6 buttons and a slider and I am having a slight issue with a fraction of the boards (button and slider layout are in the attached .png). So the issue on these boards are mostly with button 6 but sometimes with 5 and even 4 (6 is far right and buttons go down as they go left).

         

      As you can see from the pad location for the chip, it is between the buttons and the slider, I thought maybe the issue had to do with the distance the buttons were from the switch. However, when I run the program in debug mode I find that all of the buttons have very similar Cp (10-12pF). This is completely within the limits of this chip since the datasheet says SmartSense can do up to 55 pF.

         

      Another issue I thought I may have had was the plastic thickness I had over the buttons. The datasheet says up to 5mm for plastic and I am at 3mm. The test that ruled this out for me was by removing the plastic and finding that even touching the button directly had the same issue.

         

      Now when I change from SmartSense to Manual (with Run-time tuning) on some of these boards, it is able to pick up a signal wen the button is touched. On some boards this signal is weak but on others it is strong enough to trip the threshold. 

         

      Is there anything I can do to fix this problem and increase the signal? I have already tried changing the resolution and sensitivity in the CapSense module.

        • 1. Re: CapSense v2.50
          gani

          Hello,

             

          Please attach your PSoC Creator project, pdf of the schematic and gerber files of the layout for detailed analysis of the root cause.

             

          Please tell us how much SNR you are getting on the buttons. You can use CapSense Tuner to measure SNR.

             

          Please check whether there is any air gap between PCB and overlay. 

             

          Thank you,

             

          Best Regards,

             

          Ganesh.