mTouch® Slider/Wheel Configuration

A group of two to N touch button sensors can be combined to form a slider sensor that reports a linear or angular touch position. The resolution of the touch position could be set up to 12-bits. To get a position on sliders, the relative signal strength of the sensors is measured.

Common Slider Configuration

The Common Slider Settings consists of:

  • Create New Button
  • Interface Method
sliderCommonConfiguration.png

Create New Slider

The 'Create New Slider' tab in the Common Settings allows you to create an additional slider sensor for an mTouch® sensing solution project. The slider is made up of multiple segments. The 'Number of Slider(s)' defines how many sliders to be created and the 'Number of Segments(g)' defines how many segments constitute a slider. The Add button is used to add the slider to the project.

On clicking the Add button, x number of sliders and s*g number and buttons(segments) will be created. When a new slider sensor is created, the default name is Slider#, where # is the lowest number not currently used. The associated buttons will be named as Slider#_Seg$, where $ is the segment number. The individual button settings could be done by selecting them. The parameters of the buttons are explained in mTouch Button/Proximity Sensor Configuration page. The name and AKS® Group could only be modified from slider sensor settings page.

sliderSegmentConfiguration.png

Interface Method

The mTouch sensing solutions library allows your application code to obtain slider sensor status in two ways: through a callback function or through polling.

Individual Slider Sensor Configuration

The individual Slider Sensor Configuration allows you to set name, type, contact size threshold, position hysteresis, resolution, deadband percentage, and AKS group for each individual slider. The Delete Item button is used to remove the slider from the project. While removing this slider from the project, the button sensors connected to this slider is also removed.

sliderIndividualConfiguration.png

Name

This input field allows you to modify the name of the selected slider sensor. This name can be used in the code to reference this slider sensor.

Slider Type

This selection box allows you to select linear(slider) or angular(wheel) touch position for this slider sensor.

Start Segment

This text box displays you the name of the initial segment(button) associated with this slider sensor. This name could only be modified by changing the name of the slider sensor.

Contact Size Threshold

Defines the threshold for slider touch deviation, which is the sum of deviation of the most and second most touched segment to detect a user touch. It is recommended to configure the slider contact size threshold to around 50% of minimum slider touch deviation reported when sliding from end to end.

Position Hysteresis

Hysteresis is the number of positions you must move back before the new touch position is reported when the direction of scrolling is changed and during the first scroll after touch down.

Resolution

Defines the resolution of the slider in bits. A value of 8 indicates 256 positions. The slider value will be reported from to 255.

Deadband

Defines the inactive area in percentage on both ends of the slider where no change in position is reported. If the deadband is 10, then the inactive area is 10% of slider length on each end. If the slider has 8-bit resolution (0-255), but the output can only reach 25-230 due to sensor layout, then the deadband is 25, which is roughly 10% of the whole range. Setting 10% in the deadband option will remove this 10% inactive area and allows to reach the full range.

AKS Group

AKS® stands for Adjacent Key Suppression. On the slider, multiple buttons might report a detection simultaneously. To allow applications to determine the intended single touch, the mTouch library makes it possible to configure all the buttons associated with this slider sensor in a single AKS group. By default, on creating a new slider, the slider and all the associated buttons will be connected to a common new AKS Group. The AKS Group could be changed from the selection box and the associated buttons' AKG Group will be changed to the same value. When a group of buttons sensors are in the same AKS group, only the first strongest button sensor will report detection. The button or proximity sensor continues to report detection until its deviation or delta falls below its detection threshold. As long as this sensor is in the pressed state, no other button sensors in the same AKS group will report detection even if another button sensor's deviation becomes stronger in the same AKS group.

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