2 Replies Latest reply on Nov 19, 2018 5:10 AM by JoMe_264151

    PSOC 4 Kit issue with Capsense, while running on battery



      I'm not sure where to post this question.  Please move it if this is the wrong forum.


      I'm having an issue tuning CapSense buttons with my hardware.  In short, CapSense is performing differently when running the Capsense tuner over USB (board is USB powered), and when the board is running on battery power (9V battery to Vin).




      1. Setup 9 buttons and tuner in PSOC creator.  (CapSense is in Manual tuning mode)


      2. Connect PSOC 4 board via USB, and program board.


      3. Run tuner and tune all of the buttons.  Apply changes and close.


      4. Recompile, and reprogram the board.


      5. Test CapSense functionality.  Everything looks great.


      6. Disconnect USB and connect 9V battery to Vin. Everything works, except CapSense.  TheCapSense basline values are all wrong.  Touches are not recognized.  shorting a touch pad directly to ground triggers a touch, but a finger will not trigger a button.


      7. Disconnect board from battery, and connect USB cable to iPhone wallwart charger. Capsense works.


      The kit schematic shows that the PSOC 4 is powered from a 3.3V regulator.  The hardware jumper for PSOC 4 power is always 3.3V.  I'm seeing 3.3V at the PSOC 4 in all cases.  The only schematic difference I can see is a 5V line to the onboard PSOC 5, but it looks like that pin may be to check if the USB cable is connected.


      Is this a ground issue? I.e., Is CapSense perferming differently when the USB port is connected to an external ground?


      Do I need to add a 5V regulator and power the board through the USB connection, instead of 9V on Vin.