Hello,
The self-capacitance allows you to use one TSI channel per electrode. Essentially you will be able to use it like "buttons". The mutual-capacitance measures the capacitance between two electrodes connected to two TSI channels, this one could work like a "slider".
There are examples in the SDK for this mcu. You can download it in the following page. Select your FRDM-KE15z board and make sure you include all the middleware available and download it. In MCUXpresso you will find examples in two locations, when you click on "Import SDK examples" from the Quickstart panel.
One example will be located under demo_examples and the other two will be located in the driver_examples in the TSI folder.
In addition here are some application notes that may be of help:
KE15Z Touch Sensing Interface
Touch Library Reference Manual
Hope this helps. Let me know if you have any further questions.
Best Regards,
Sabina
