CapTIvate™ Touch MCUs
- SLAU857A May 2021 – July 2021 MSP430FR2476 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR2672 , MSP430FR2673 , MSP430FR2675 , MSP430FR2676

CapTIvate™ Touch MCUs

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IMPORTANT NOTICE

Full reading width

GETTING STARTED

CapTIvate™ Touch MCUs

Trademarks

CapTIvate, MSP430, and Code Composer Studio are trademarks of Texas Instruments Incorporated.

All trademarks are the property of their respective owners.

1 Introduction

1.1 Overview

Physical button, knobs, and sliders experience the following shortcomings compared to capacitive touch controls. Physical controls:

Experience wear and decreased reliability after prolonged use.
Require a gap between the front panel and the buttons, which is easy to be penetrated by moisture that can cause defects.
Require the user to exert force to trigger.
Require openings in the front panel that can increase cost to a certain extent.
Have relative fixed shapes.

TI CapTIvate™ capacitive touch technology supports five sensor types: buttons, proximity sensors, scroll wheels, sliders, and touch panels, and a variety of covering materials. CapTIvate technology supports low power consumption, strong and stable induction technology, strong anti-noise ability, and allows for waterproof construction.

This document helps with the capacitive touch development process and helps you quickly understand the full features of TI CapTIvate capacitive touch technology.

For a preliminary function evaluation, see Section 2, Section 3, and Section 6.
For hardware and mechanical structure development, see Section 2, Section 3, and Section 4.
For software development, see Section 3, Section 5, and Section 6.

Figure 1-1 Capacitive Touch Development Process

1.2 Terms and Abbreviations

Term	Definition
Base capacitance	The parasitic capacitance of the sensor before the finger touches it
BSL	Bootloader
CAP I/O	A pin on an MSP430™ MCU that is dedicated to the capacitive touch function
CapTIvate	TI’s capacitive touch design system
FRAM	Ferroelectric RAM (also FeRAM or F-RAM)
GUI	Graphical user interface
IDE	Integrated development environment
JTAG	JTAG (named after the Joint Test Action Group) is an industry standard for verifying designs, testing printed circuit boards programming and debugging after manufacture
LPM0, LPM3, LPM4	Different low-power modes of MSP430 MCUs. For specific power consumption, see the device-specific data sheet.
MSP	Mixed signal processor
NVM	Nonvolatile memory
Rx	In mutual-capacitance mode or self-capacitance mode, the pin or electrode responsible for charging from the parasitic capacitance to the internal reference capacitance of the MCU.
SBW	2-wire Spy-Bi-Wire interface, a typical JTAG interface for MSP430 MCUs
Tx	In mutual-capacitance or self-capacitance mode, the pin or electrode responsible for charging the parasitic capacitance.

2 Principles of Capacitive Touch

Figure 2-1 shows a common capacitive touch sensor. Sensors typically use copper on the PCB as electrodes. The top layer is covered with a nonconductive protective layer, such as glass or plastic, and glued to the PCB. A grid ground surrounds the sensor.

Figure 2-1 Capacitive Touch Structure

Based on the type of capacitance detected, capacitive touch can be described as self-capacitive detection (detecting the capacitance value between a single electrode and power line ground) or mutual-capacitive detection (detecting the capacitance value between two electrodes).