SLAA877 December   2018 MSP430FR2633

 

  1.   Capacitive Touch Gesture Software and Tuning
    1.     Trademarks
    2. 1 Introduction
    3. 2 Gestures
      1. 2.1 Theory of Operation
      2. 2.2 Sensor Gesture Processing
      3. 2.3 Gesture Software Overview
        1. 2.3.1 Slider Gesture
        2. 2.3.2 Wheel Gesture
        3. 2.3.3 Button Gesture
        4. 2.3.4 Sensor Handlers
        5. 2.3.5 How to Add Gestures to the CapTIvate Framework
    4. 3 Tuning
      1. 3.1 CapTIvate Design Center
        1. 3.1.1 Enabling Gesture Sensor Output
        2. 3.1.2 CDC Plot Channel Assignments
      2. 3.2 Tuning Process
        1. 3.2.1 Tap
        2. 3.2.2 Double Tap
        3. 3.2.3 Swipe
        4. 3.2.4 Slide
    5. 4 Example Demonstration Software Installation
      1. 4.1 Project Directories
      2. 4.2 Import the Project Into CCS

3.2 Tuning Process

The default sensor sample rate, sensor timing and motion parameters in the example gesture software have been selected to provide good sensor response with the CAPT-BSWP board. Each sensor's gesture time and motion parameters are configurable and can be tuned for different gesture responsiveness. You are encouraged to experiment with the sensor gesture parameters and sample rate settings.

To change the sensor sampling rate, modify the g_uiApp data structure element found at the very end of the file CAPT_UserConfig.c as shown here. Keep in mind this file will be overwritten if updated from the CapTIvate Design Center.

.ui16ActiveModeScanPeriod = 10,

Build and reprogram the MSP430FR2633 target MCU.

To see how the gesture tuning process works,perform all the steps above to enable streaming the slider gesture data to the CapTIvate Design Center. While data is being displayed, perform a tap on the slider sensor. The sensor's sample count, touch status and gesture output should appear in the oscilloscope view. Make sure the appropriate channels for the Tap gesture are enabled. Experiment with fast and slow finger taps. If your tap gesture meets the min and max timing parameters your plot should appear similar to the Valid Tap example shown in Figure 5.

If your finger tap is slow, the gesture may not be detected because the finger was touching too long and the ui16TouchSampleCount_Max parameter was exceeded. In this case your plot will look similar to the Invalid Tap example shown inFigure 7 . Try the tap again but this time the finger should touch only briefly.

If you finger tap is too quick, the gesture may not be detected because the finger was not touching long enough and did not meet the ui16TouchSampleCount_Min parameter. The plot should appear similar to the Invalid Tap example shown in Figure 6 . If you desire a quicker response, modify the ui16TouchSampleCount default value from 3 to 2, or possibly 1. With the sample rate at 20msec, going from 3 to 1 is effectively decreasing the time from 60msec to 20msec. Build and reprogram the MSP430FR2633 target MCU. Test again to see if the gesture detects the tap reliably.

Experiment with the swipe and slide gesture to see how the time and distance parameters affect the sensor's responsiveness. Adjust accordingly to achieve your desired response.