Generate Mutual Cap Parallel Acquisition Project


Mutual Capacitance Button

Create a User Board project for Mutualcap technology from Sensors > Button > Technology > Mutualcap from within the QTouch® Configurator. (Refer to the "Generate a QTouch Configurator Project" page for more details.)



Sensor Layout View



Enabling Parallel Acquisition

After configuring the sensors and pins, to enable the parallel acquisition, select the ‘Enable Parallel Acquisition for Improved SNR’ checkbox.



Pin Selection View


The mutual capacitance sensors are grouped down as per the Y-lines. If the total number of sensors for a given Y line is more than four, multiple groups are formed with four X-lines for each group. The group information can be found in touch.h file as illustrated below.

For a given Y line, if the number of sensors is less than four or if the number of sensors is not a multiple of four, virtual sensors named X_NONE are added to the group in that Y-line.

In the above example configuration, Y0 will not have X_NONE and the Y2 group will have two X_NONE as shown below.


The acquisition parameters (like filter level, prescaler, CSD etc) for the group is decided by the maximum values configured for the corresponding Y line.


Node Mapping Information


If the number of sensors is not a multiple of four or if each Y line does not have a multiple of four sensors, then the total number of nodes and buttons does not match. Even if everything is multiple of four, the buttons may not be sequentially assigned for a given Y line. So, to map the node to an individual button, an array is created in the touch.c file. The array ‘touch_key_node_mapping_4p’ in the touch.c file displays the button’s position in the group created.


Data Streamer

The Datastreamer displays only the available buttons in the ‘Sensors’ tab and not the X_NONEs.


Additional Group Example


If the sensors are interchanged as above, the following changes reflects in both touch.h and touch.c file.

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