NXP Semiconductors MKW01Z128, Reference Manual, Page: 818 / 884

Chapter 35
Touch Sensing Input (TSI)
35.1 Introduction
The touch sensing input (TSI) module provides capacitive touch sensing detection with
high sensitivity and enhanced robustness.
Each TSI pin implements the capacitive measurement by a current source scan, charging
and discharging the electrode, once or several times. A reference oscillator ticks the scan
time and stores the result in a 16-bit register when the scan completes. Meanwhile, an
interrupt request is submitted to CPU for post-processing if TSI interrupt is enabled and
DMA function is not selected.The TSI module can be periodically triggered to work in
low power mode with ultra-low current adder and wake CPU at the end of scan or the
conversion result is out of the range specified by TSI threshold. It provides a solid
capacitive measurement module to the implementation of touch keyboard, rotaries and
sliders.
35.1.1 Features
TSI features includes:
• Support up to 16 external electrodes
• Automatic detection of electrode capacitance across all operational power modes
• Internal reference oscillator for high-accuracy measurement
• Configurable software or hardware scan trigger
• Fully support Freescale touch sensing software (TSS) library, see
www.nxp.com/
touchsensing .
• Capability to wake MCU from low power modes
• Compensate for temperature and supply voltage variations
• High sensitivity change with 16-bit resolution register
• Configurable up to 4096 scan times.
• Support DMA data transfer
• The auxiliary noise detection mode supplies improved EMC immunity.
MKW01Z128 MCU Reference Manual, Rev. 3, 04/2016
Freescale Semiconductor, Inc. 687