49.5.1 I/O Lines
The I/0 lines used for analog X-lines and Y-lines must be connected to external capacitive touch sensor electrodes. External components are not required for normal operation. However, to improve the EMC performance, a series resistor of 1kΩ or more can be used on X-lines and Y-lines.
Mutual-Capacitance Sensor Arrangement
A mutual-capacitance sensor is formed between two I/0 lines - an X electrode for transmitting and Y electrode for sensing. The mutual capacitance between the X and Y electrode is measured by the Peripheral Touch Controller.
Self-Capacitance Sensor Arrangement
A self-capacitance sensor is connected to a single pin on the Peripheral Touch Controller through the Y electrode for sensing the signal. The sense electrode capacitance is measured by the Peripheral Touch Controller.
For more information about designing the touch sensor, refer to Buttons, Sliders and Wheels Touch Sensor Design Guide.