Information

Chapter 52

Touch sense input (TSI)

52.1 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 for the implementation of touch keypad, rotaries and sliders.

52.2 Features

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

registers

• Automatic detection of electrode capacitance change with programmable upper and

lower threshold

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

• Full support with FSL touch sensing SW library (TSS) for 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

• Compensate temperature and supply voltage variations

• Stand alone operation not requiring any external crystal even in low power modes

K20 Sub-Family Reference Manual, Rev. 6, Nov 2011

Freescale Semiconductor, Inc. 1567