2 Replies Latest reply on Dec 2, 2019 3:44 AM by AH_96

    Trouble getting CapSense to start the same each time at power up


      I am doing a project that uses 5 capsense buttons to operate a locking mechanism in my project. I m having issues that when i power up the unit by placing batteries into the unit it some times does not operate properly.  There are times I only get 4 buttons to work or I get only one button to work.  Most the time is does work properly were all 5 buttons work great. In the design i am using the shield option and activated sense my project will be around water a significant amount of time.

      CapSense Setup:

      I have a 2.2nF cap on the Cmos pin and a 10nF cap on the Csh pin.


      The board is a four layer board in which i followed the guidelines suggested in getting started with capsense. i followed the guidelines in AN85951 page 110.

      Top layer: Hatch fill 7-mill and 45-mil grid ... connected to shield.

      Layer-2: Hatch fill 7-mill and 70-mill grid ... connected to shield.

      Layer 3: Solid Plane ... connected to Gnd

      Bottom Layer: Hatch fill 7-mill and 70-mill grid ... connected to Gnd


      I have attached my project for review.


      I was hoping i could get some help as to why my capsense is not working constantly all the time at power.  I my board is need for review let me know and i will post it if necessary.