Information

Chapter 48

Touch sense input (TSI)

48.1 Introduction

NOTE

For the chip-specific implementation details of this module's

instances see the chip configuration chapter.

The touch sensing input (TSI) module provides capacitive touch sensing detection with

high sensitivity and enhanced robustness. Each TSI pin implements the capacitive

measurement of an electrode having individual programmable detection thresholds and

result registers. The TSI module can be functional in several low power modes with ultra

low current adder and waking up the CPU in a touch event. It provides a solid capacitive

measurement module to the implementation of touch keypad, rotaries and sliders.

48.2 Features

TSI module features included:

• Support as many as 16 input capacitive touch sensing pins with individual result

registers

• Automatic detection of electrode capacitance change in low power mode with

programmable upper and lower threshold

• Automatic periodic scan unit with different duty cycles for run and low power modes

• Fully support with FSL touch sensing SW library suite the implementation of

keypads, rotaries and sliders

• Operation across all low power modes: WAIT,STOP, VLPR, VLPW, VLPS,

LLS,VLLS{3,2,1}

• Capability to wake up MCU from low power modes.

• Configurable interrupts:

• End-of-scan or out-of-range interrupt

• TSI error interrupts: pad short to V

or conversion overrun

K20 Sub-Family Reference Manual, Rev. 2, Feb 2012

Freescale Semiconductor, Inc. 1187