1 Reply Latest reply on Jun 20, 2018 12:21 AM by ShanmathiN_06

    CY8CMBR3xxx - poor response time for first touch button




      in my application I use CY8CMBR3116-LQXI with two buttons, guard and shield usage, no proximity, no slider. TouchController and my Host MCU are connected via i2c and interrupt line. So when button status change is recognized, interrupt line is driven and button status is read out by my host controller. Host controller resets touchController every two seconds and autotuning is activated, due to environmental changes (outside application). If touch activity occurs, periodic two-seconds-reset is skipped for 60 seconds. I have some a few mm overlay and a small air gap. Not best conditions, but working in principle.


      Noticed behaviour of touch functionality is as follows:

      • after first successful recognition of one of the two touch buttons, all following touch activities are recognized well
      • after approx. several minutes without interaction, one have to press longer (about 1-3 seconds) to achieve first touch recognition



      So it seems as if touchController is in kind of "sleep mode". Since our application has own power supply unit, sleep mode is not needed.

      According to Operating Modes described in CY8CMBR3xxx Design Guide Section 7.1, we have stateTimeout configured to 10 seconds. As controller is reset every two seconds, it should never reach DeepSleep.



      From design_toolbox excel sheet, section "Cp, Power Consumption Calculator" I learned, deactivating IIR Filter and Median Filter and reducing Debounce as well as low scan period decreases "Response time for first button touch". Is it right direction I am heading for?

      However, my config is:

      • IIR = Median = enabled
      • Debounce = 3
      • ScanPeriod = 50 counts/0.1 pF


      Changing these values to IIR=Median=disabled and debounce=1 do not solve my issue.


      Which parameters should I change to decrease response time for first button touch?

      Is it helpful when I provide data from ez-click CapSense output? Which data do you need?


      Best regards

        • 1. Re: CY8CMBR3xxx - poor response time for first touch button



          1)  Yes, you are right. This may be because MBR3 is in sleep mode.

          You could set the Scan period in CapSense sensor configuration tab of Ez-Click to 20 ms. (This is the scan rate in look for touch touch mode)


          You could increase the state timeout further, to prolong the active state.


          The controller will not go to deep sleep mode, unless a sleep command is issued. You could refer to section 7.1 you have mentioned earlier.


          2) Yes, changing debounce to 1 and disabling IIR and median filters should help.


          Please try the above and update the response time behaviour.