Microchip Technology mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

mTouch™ Advanced Capacitive

Evaluation Kits

User’s Guide

Note the following details of the code protection feature on Microchip devices:

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Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.

Trademarks

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EELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,

PIC

logo, rfPIC and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

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Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

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All other trademarks mentioned herein are property of their respective companies.

Printed on recycled paper.

ISBN: 978-1-60932-298-4

Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and T empe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC devices, Serial EEPROMs, microperipherals, nonvolatile memo ry and analog products. In addition, Microchip’s quality system for the desig n and manufacture of development systems is ISO 9001:2000 certified.

MCUs and dsPIC® DSCs, KEELOQ

code hopping

mTouch™ ADVANCED CAPACITIVE EVAL-

UATION KITS USER’S GUIDE

Table of Contents

Preface ........................................................................................................................... 5

Introduction............................................................................................................5

Document Layout.................................................................................................. 5

Conventions Used in this Guide............................................................................6

Warranty Registration............................................................................................7

Recommended Reading........................................................................................7

The Microchip Web Site...................................................................................... 10

Development Systems Customer Change Notification Service .......................... 10

Customer Support...............................................................................................11

Document Revision History.................................................................................11

Chapter 1. Introduction to the Evaluation Boards

1.1 Overview ......................................................................................................13

1.2 Operational Requirements ...........................................................................15

1.3 Initial Board Setup ........................................................................................ 16

Chapter 2. Demonstration Application

2.1 Introduction to the Touch Interface ...............................................................17

2.2 Individual Touch Sense Demonstrations ...................................................... 18

Chapter 3. Using the mTouch™ Sensing Solution

3.1 About the mTouch Sensing Solution Diagnostic Tool .................................. 21

3.2 MPLAB IDE integrated mTouch Diagnostic Tool GUI ..................................21

Chapter 4. Evaluation Board Hardware

4.1 Application Functional Overview .................................................................. 27

4.2 Board Components ......................................................................................32

4.3 Interfacing to the Evaluation Boards ............................................................38

Chapter 5. Troubleshooting

5.1 Common Issues ...........................................................................................41

Appendix A. Evaluation Board Schematics Appendix B. mTouch™ PIC16F CSM State Diagrams

Index .............................................................................................................................53

Worldwide Sales and Service ....................................................................................54

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

mTouch™ ADVANCED CAPACITIVE

EVALUATION KITS USER’S GUIDE

Preface

NOTICE TO CUSTOMERS

All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available.

Documents are identified with a “DS” number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the document.

For the most up-to-date information on development tools, see the MPLAB Select the Help menu, and then Topics to open a list of available online help files.

INTRODUCTION

This chapter contains general information that will be useful to know before you use an mT ouch™ Advanced Ca pacitive Evaluation Kit. Items discussed in this chapter include:

• Document Layout

• Conventions Used in this Guide

• Warranty Registration

• Recommended Reading

• The Microchip Web Site

• Development Systems Customer Change Notification Service

• Customer Support

• Document Revision History

IDE online help.

DOCUMENT LAYOUT

This document describes how to use an mT ouch Advanced Capacitive Evaluation Kit as a development and demonstrative tool for PIC16F, PIC18F, PIC24F, PIC24H and PIC32MX MCU device capabilities and features. The document layout is as follows:

• Chapter 1. Introduction to the Evaluation Boards – This chapter introduces the mTouch Advanced Capacitive Evaluation Kits and provides an overview of their features.

• Chapter 2. Demonstration Application – This chapter describes the preprogrammed capacitive touch sense demonstration application.

• Chapter 3. Using the mTouch™ Sensing Solution – This chapter describes the diagnostic software and how to use it with an mTouch Advanced Capacitive Evaluation Kit.

• Chapter 4. Evaluation Board Hardware – This chapter provides a functional overview of the mTouch Advanced Capacitive Evaluation Kits and identifies the major hardware components.

• Chapter 5. Troubleshooting – This chapter provides troubleshooting tips for commonly encountered issues.

• Appendix A. “Evaluation Board Schematics” – This appendix provides

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

detailed schematic diagrams of the evaluation boards.

• Appendix B. “mTouch™ PIC16F CSM State Diagrams” – This appendix provides PIC16F CSM state diagrams.

CONVENTIONS USED IN THIS GUIDE

This manual uses the following documentation conventions:

DOCUMENTATION CONVENTIONS

Description Represents Examples

Arial font:

Italic characters Referenced books MPLAB® IDE User’s Guide

Emphasized text ...is the only compiler...

Initial caps A window the Output window

A dialog the Settings dialog A menu selection select Enable Programmer

Quotes A field name in a window or

dialog

Underlined, italic text with right angle bracket

Bold characters A dialog button Click OK

Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>

Courier New font:

Plain Courier New Sample source code #define START

Italic Courier New A variable argument file.o, where file can be

Square brackets [ ] Optional arguments mcc18 [options] file

Curly brackets and pipe character: { | }

Ellipses... Replaces repeated text var_name [,

A menu path File>Save

A tab Click the Power tab

Filenames autoexec.bat File paths c:\mcc18\h Keywords _asm, _endasm, static Command-line options -Opa+, -Opa- Bit values 0, 1 Constants 0xFF, ‘A’

Choice of mutually exclusive arguments; an OR selection

Represents code supplied by user

“Save project before build”

any valid filename

[options] errorlevel {0|1}

var_name...] void main (void)

{ ... }

WARRANTY REGISTRATION

Please complete the enclosed Warran ty Registration Card and mail it promptly. Sending in the Warranty Registration Card entitles you to receive new product updates. Interim software releases are available at th e Microchip web site.

RECOMMENDED READING

This user’s guide describes how to use an mTouch Advanced Capacitive Evaluation Kit. Other useful documents are listed below. The following Microchip documents are available and recommended as supplemental reference resources. The latest documentation is available from the mTouch web page (www.microchip.com/mtouch).

Readme Files

Preface

For the latest information on using other tools, read the tool-specific Readme files in the Readme subdirectory of the MPLAB contain update information and known issues that may not be included in this user’s guide.

IDE installation directory. The Readme files

Family Reference Manual Sections

Family Reference Manual sections are available, which explain the operation of the PIC microcontroller family architecture and peripheral modules. The specifics of each device family are discussed in the individual family’s device data sheet.

Users are specifically directed to the “Charge Time Measurement Unit (CTMU)” Family Reference Manual sections for a detailed discussion of this module, which is at the heart of the capacitive touch sense demonstration. Please refer to the Microchip web site for the latest version of these documents.

Device Data Sheets and Flash Programming Specifications

Refer to the appropriate device data sheet for device-specific information and specifications. Also, refer to the appropriate device Flash Programming Specification for information on instruction sets and firmware development. These documents may be obtained from the Microchip web site or your local sales office.

16-bit MCU and DSC Programmer’s Reference Manual (DS70157)

This manual is a software developer’s reference for the 16-bit PIC24F and PIC24H MCU, and 16-bit dsPIC30F and dsPIC33F DSC families of devices. It describes the instruction set in detail and also provides general information to assist in developing software for these device families.

Note: Refer to “MIPS32

Instruction Set” at www.mips.com for related information on PIC32 MCUs.

Architecture for Programmers Volume II: The MIPS32®

MPLAB® Assembler Linker and Utilities for PIC24 MCUs and dsPIC® DSCs User’s Guide (DS51317)

This document details Microchip Technology’s language tools for dsPIC® DSC devices based on GNU technology. The language tools discussed are:

DSCs

• MPLAB Assembler PIC24 MCUs and dsPIC

• MPLAB Linker PIC24 MCUs and dsPIC

• MPLAB Archiver/Librarian PIC24 MCUs and ds PIC

• Other Utilities

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

MPLAB® Assembler Linker and Utilities for PIC32 MCUs User’s Guide (DS51833)

This document details Microchip Technology’s language tools for PIC32 MCU devices based on GNU technology. The language tools discussed are:

• MPLAB Assembler PIC32 MCUs

• MPLAB Linker PIC32 MCUs

• MPLAB Archiver/Librarian PIC32 MCUs

• Other Utilities

HI-TECH C® for PIC10/12/16 User’s Guide (DS51865)

This document details the use of Microchip’s HI-TECH C Compiler for PIC10/12/16 MCUs, which is a free-standing, optimizing ANSI C compiler. It supports all PIC10, PIC12 and PIC16 series devices, as well as the PIC14000 device and the enhanced Mid-Range PIC

MPLAB® C Compiler for PIC18 MCUs User’s Guide (DS51288)

This document details the use of Microchip’s MPLAB C Compiler for PIC18 MCU devices to develop an application. The MPLAB C Compiler is a GNU-based language tool, based on source code from the Free Sof tware Foundation (FSF). For more information about the FSF, see www.fsf.org.

MCU architecture.

MPLAB® C Compiler for PIC24 MCUs and dsPIC® DSCs User’s Guide (DS51284)

This document details the use of Micr ochip’s MPLAB C Compiler for PIC24 MCUs and dsPIC DSC devices to develop an application. The MPLAB C Compiler is a GNU-based language tool, based on source code from the Free Sof tware Foundation (FSF). For more information about the FSF, see www.fsf.org.

MPLAB® C Compiler for PIC32 MCUs User’s Guide (DS51686)

This document details the use of Microchip’s MPLAB C Compiler for PIC32 MCU devices to develop an application. The MPLAB C Compiler is a GNU-based language tool, based on source code from the Free Sof tware Foundation (FSF). For more information about the FSF, see www.fsf.org.

MPLAB® REAL ICE™ In-Circuit Emulator User’s Guide (DS51616)

This document describes how to use the MPLAB REAL ICE in-circuit em ulato r as a development tool to emulate and debug firmware on a tar get board, as we ll as how to program devices.

MPLAB® IDE User’s Guide (DS51519)

This document describes how to use the MPLAB IDE Integrated Development Environment, as well as the MPLAB project manager, MPLAB editor and MPLAB SIM simulator . Use these development tools to help you develop and debug application code.

Preface

Application Notes

There are several Application Notes available from Microchip that help in understanding capacitive touch applications. These include:

• AN1101 “Introduction to Capacitive Sensing”

• AN1102 “Layout and Physical Design Guidelines for Capacitive Sensing”

• AN1103 “Software Handling for Capacitive Sensing”

• AN1104 “Capacitive Multibutton Configurations”

• AN1171 “Using the Capacitive Sensing Module on the PIC16F72X”

• AN1202 “Capacitive Sensing with PIC10F”

• AN1250 “Microchip CTMU for Capacitive Touch Applications”

• AN1298 “Capacitive Touch Using Only an ADC (“CVD”)”

Microchip mTouch™ Sensing Solutions Webinars

Currently, there are three online Webinars available for mTouch Sensing Solutions:

• Introduction to mTouch™ Capacitive Touch Sensing

• Capacitive mTouch™ Sensing Solutions: Design Guidelines

• Overview of Charge Time Measurement Unit (CTMU)

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

THE MICROCHIP WEB SITE

Microchip provides online support through our web site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information:

• Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s guides and hardware support documents, latest software releases and archived software

• General Technical Support – Frequently Asked Questions (FAQs), technical support requests, online discussion groups, Microchip consultant program member listing

• Business of Microchip – Product selector and ordering guides, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives

DEVELOPMENT SYSTEMS CUSTOMER CHANGE NOTIFICATION SERVICE

Microchip’s customer notification service helps keep customers current on Microchip products. Subscribers will receive e-mail notification whenever there are changes, updates, revisions or errata related to a spec ified product family or development tool of interest.

To register, access the Microchip web site at www.microchip.com, click on Customer Change Notification and follow the registration instructions.

The Development Systems product group categories are:

• Compilers – The latest information on Microchip C compilers a nd other language tools. These include the MPLAB C compiler; MPASM™ and MPLAB 16-bit assemblers; MPLINK™ and MPLAB 16-bit object linkers; and MPLIB™ and MPLAB 16-bit object librarians.

• Emulators – The latest information on Microchip in-circuit emulators.This includes the MPLAB ICE 2000, MPLAB ICE 4000, MPLAB REAL ICE.

• In-Circuit Debuggers – The latest information on the Microchip in-circuit debugger, MPLAB ICD 2, and MPLAB ICD 3.

• MPLAB Integrated Development Environment for development systems tools. This list is focused on the MPLAB IDE, MPLAB SIM simulator, MPLAB IDE Project Manager and general editing and debugging features.

• Programmers – The latest information on Microchip programmers. These include the MPLAB PM3 and PRO MATE Plus and PICkit™ 1, 2 and 3 development programmers.

IDE – The latest information on Microchip MPLAB IDE, the Windows®

II device programmers and the PICSTART®

CUSTOMER SUPPORT

Users of Microchip products can receive assistance through several channels:

• Distributor or Representative

• Local Sales Office

• Field Application Engineer (FAE)

• Technical Support Customers should contact their distributor, representative or FAE for support. Local

sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document.

Technical support is available through our web site at: http://support.microchip.com

DOCUMENT REVISION HISTORY

Revision A (April 2009)

• Initial Release of this Document

Revision B (September 2009)

• Added reference to PIC18F MCU

• Added PIC18F CTMU Evaluation Board Schematic

• Added PIC18F Block Diagram for the CTMU Board

• Modified the Kit Contents list

Preface

Revision C (June 2010)

This version of the document includes the following updates:

• Added references to PIC24H and PIC32MX MCUs throughout the document

• Modified the Kit Contents list

• Added the PIC32 CVD Touch Evaluation Board

• Added block diagrams for the PIC24H CVD and PIC32 CVD Evaluation Boards

• Updated PIC16F CSM/CVD Evaluation Board schematic and layout

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

NOTES:

mTouch™ ADVANCED CAPACITIVE

EVALUATION KITS USER’S GUIDE

Chapter 1. Introduction to the Evaluation Boards

Thank you for purchasing a Microchip Technology mTouch Advanced Capacitive Evaluation Kit. Depending on the kit purchased, up to four individua l evaluation boards are provided. These ev aluation boards a re inten ded to intr od uce a nd de mon strate the possibilities for capacitive touch sense applications on the PIC16F, PIC18F, PIC24F, (DM183026-2 kit), PIC24H (AC243026 kit) and PIC32MX microcontroller platforms.

Note: This Evaluation Kit is intended as a functional evaluation of Microchip’s

mTouch Capacitive Sensing Solutions. It has not been designed for use in noisy or production - level testing environment. Please refer Microchip Application Notes for guidelines when attempting to design a product to be used or deployed in such environments.

This chapter introduces the evaluation kits and provides an overview of th eir features. Topics covered include:

•Overview

• Operational Requirements

• Initial Board Setup

1.1 OVERVIEW

The mTouch Advanced Capacitive Evaluation Kits provide a simple platform for developing a variety of capacitive touch sense applications. Depending on the kit purchased, up to four evaluation boards are included with PIC16F, PIC18F, PIC24F, PIC24H and PIC32MX microcontrollers, with four sensor daughter boar ds, as shown in Figure 1-1 and Figure 1-2.

These evaluation kits are intended to be used to develop a capacitive touch sense application using Microchip’s mTouch technologies. A kit is used by first connecting a sensor board, and then supplying power to the board via USB, PICkit™ 3 or the PICkit Serial Analyzer . The connector, J3/J4, with numbers from 0 to 15, is the connector for sensing channels. The numbers, from 0 to 15 for PIC16F, PIC24F, PIC24H and PIC32MX, and from 0 to 12 for PIC18F, represents the microcontroller’s sensing channel. The vertical 2-row header is for debugging, to give easy access to some of the microcontroller pins. Debugging may also be done by Microchip programmers and the I

When using an evaluation kit out of the box, the default function of the LEDs is to illuminate on a key press. All functionalities may be reprogrammed by using a Microchip programmer and reprogramming the firmware in the device. The firmware supplied with the evaluation kit is optimized to use with the four sensor boards supplied.

The USB connection supplies power to the board; no additional external power supply is needed. For independent operation, the ev al ua ti o n board may be discon nected from the PC and powered at test points. For the PIC18F, PIC24F and PIC32MX evaluation boards, the USB also provides communications with the MPLAB mTouch Diagnostic Tool. The PIC16F and PIC24H evaluation boards use the PICkit Serial Analyzer to communicate via I monitor the performance of the touch sensors and to optimize the sensor response. A separate, 6-wire programming interface allows users to replace the preprogrammed

C™ or USB is used to communicate with the mTouch diagnostic tool.

C to the PC. The MPLAB mTouch application allows users to

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

demonstration firmware with their own applications using Microchip’s MPLAB Integrated Development Environment (IDE) and In-Circuit Serial Programming™ (ICSP™). This allows the board to also be used as a test platform for capacitive touch sense applications.

1.1.1 mTouch Advanced Capacitive Evaluation Kit Contents

The mT ou ch Advanced Capacitive Evaluation Kit (D M183026-2) contains th e following items:

• PIC16F CSM Evaluation Board

• PIC18F CVD/CSM Evaluation Board

• PIC24F CTMU Evaluation Board

• PIC32MX CVD Evaluation Board

• 12-Key Matrix Sensor Daughter Board

• 4-Channel Slider Sensor Daughter Board

• 2-Channel Slider Sensor Daughter Board

• 8-Key Direct Sensor Daughter Board

• PICkit Serial Analyzer

• USB Cable

FIGURE 1-1: mTouch™ ADVANCED CAPACITIVE EVALUATION KIT

CONTENTS

Introduction to the Evaluation Boards

1.1.2 PIC24H Capacitive Touch Evaluation Kit Contents

The PIC24H Capacitive Touch Evaluation Kit (AC243026) contains the following items:

• PIC24H CVD Evaluation Board

• 8-Key Direct Sensor Board

• 12-Key Matrix Sensor Board

• 4-Channel Slider Sensor Board

• 2-Channel Slider Sensor Board

• PICkit Serial Analyzer

• USB Cable

FIGURE 1-2: PIC24H CAPACITIVE TOUCH EVALUATION KIT CONTENTS

1.2 OPERATIONAL REQUIREMENTS

T o communicate with , and to program an evaluation board, the following hardwa re and software requirements must be met:

• PC-compatible system with a CD-ROM drive

• One available USB port on the PC or a powered USB hub

•Microsoft

Windows® XP SP2, Windows 7, or Windows Vista (32-bit)

mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

1.3 INITIAL BOARD SETUP

With its pre-installed demonstration a pplication, the evaluation board is designed to be used straight out of the box. Except for a single connection to a computer , no additional hardware or configuration is necessary.

1.3.1 Installing the Software

Before connecting the eva lu at ion board to any computer for th e first time, it is important to install the PC software found on the accompanying CD first. This ensures that the proper USB drivers for communicating with the e valu ati on board are in stalled and ready to recognize the board.

To install the software and driver, insert the evaluation kit CD into the CD-ROM drive. The installation process starts automatically. The process pauses for user responses to accept the Microchip software licenses, and to confirm the installation directories; you must accept the license to use the software.

1.3.2 Connecting the Hardware

Prior to connection, place the evaluation board on a flat surface near the computer. Check to make sure that there are no objects underneath the board. Once the evaluation kit sof tware is installed, connect the provided USB cable (A to mini-B) to any available USB port on the PC or powered hub, and then to the board at the mini-B receptacle. The PC USB connection provides power to the board.

The PIC24F and PIC18F CTMU and PIC32MX Capacitive Voltage Divider (CVD) evaluation boards use the USB connection to power up the boards and also to communicate with the mTouch diagnostic tool. The PIC16F Cap Sense Module (CSM) and PIC24H CVD evaluation boards use the PICkit Serial Analyzer to communicate to the PC. Connect the USB cable to the PICkit Serial Analyzer, and connect it to the J2 connector on the board and the PC’s USB port. The default code uses the 8-button board.

When connecting the PIC24F and PIC18F CTMU and PIC32MX CVD boards, a sequence of pop-up messages should appear in the system tray (lower right of the desktop), stating that (1) new hardware has been fou nd, (2) drivers ar e being inst alled and (3) the new hardware is ready for use. If you do not see these messages and the eval u at io n board does not work, try u nplugging and reconnecting th e USB cable. If this does not work, see Chapter 5. “Troubleshooting”.

mTouch™ ADVANCED CAPACITIVE

EVALUATION KITS USER’S GUIDE

Chapter 2. Demonstration Application

This chapter describes the touch sense application that is preprogrammed on the PIC16F, PIC18F, PIC24F, PIC24H and PIC32MX microcontrollers, and its general principles of operation. Topics included in this chapter are:

• Introduction to the Touch Interface

• Individual Touch Sense Demonstrations

2.1 INTRODUCTION TO THE TOUCH INTERFACE

For PIC24H and PIC32MX MCUs, touch sensing is achieved using a technique known as the Capacitive Volt age Divider, which makes use of the ADC module. This technique is based on successive charging/discharging cycles for sample and hold capacitance and conversely, sensor plus finger capacitance, which basically cr eates a voltage divider. For details, refer the application note, AN1298 “Capacitive Touch Using Only an ADC (“CVD”)” .

Control of the touch sense features is built on the PIC18F and PIC24F microcontrollers’ on-chip Charge Time Measurement Unit (CTMU) module. The CTMU consists of a constant current source that charges each touch circuit to a voltage level. When any additional capacitance is added to the circuit (from the touch of a fingertip, for example), the fixed current source will now charge the circuit to a lower voltage. This change is how the microcontroller detects a touch event. For detailed information on the CTMU module, please refer to the related “Charge Time Measurement Unit (CTMU)” Family Reference Manual sections, which are available from the Microchip web site.

On the PIC16F CSM Evaluation Board, the on-chip Cap Sense Module (CSM) creates a relaxation oscillator to perform touch sensing. The period or frequency of the relaxation oscillator can be measured, and when the sensor is touched, the frequency will drop and the period will increase, indicating a touched condition.

The microcontrollers use the CTMU, CVD or CSM to monitor it s input channels, which are in turn, connected to capacitive touch pad sensors on the top layer of the circuit board.

The evaluation board has four different sensor demonstration boards:

• 8-Key Direct Plug-in Daughter Board

• 12-Key Matrix Plug-in Daughter Board

• 2-Channel Slider Plug-in Daughter Board

• 4-Channel Slider Plug-in Daughter Board A more detailed description of the e valuation boards ’ operation is pr ovided in Chapter

4. “Evaluation Board Hardware”.

2.1.1 Touch Sensitivity

The response of the sensor to fingertip touch is influenced by many factors: touch areas, voltage and current levels, ambient humidity, static buildup, and so on. The capacitive touch sensing is done by a relative shift in the capacitance due to the addition of the finger capacitance to the touch sensor. The demonstration code supplied takes most of the typical environmental factors into consideration. The demonstration application is very flexible in the sense that it can be modified by the user.

+ 37 hidden pages

Microchip Technology mTouch™ Advanced Capacitive Evaluation Kits User’s Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Chapter 1. Introduction to the Evaluation Boards

1.1 OVERVIEW

1.1.1 mTouch Advanced Capacitive Evaluation Kit Contents

1.1.2 PIC24H Capacitive Touch Evaluation Kit Contents

FIGURE 1-2: PIC24H CAPACITIVE TOUCH EVALUATION KIT CONTENTS

1.2 OPERATIONAL REQUIREMENTS

1.3 INITIAL BOARD SETUP

1.3.1 Installing the Software

1.3.2 Connecting the Hardware

Chapter 2. Demonstration Application

2.1 INTRODUCTION TO THE TOUCH INTERFACE

2.1.1 Touch Sensitivity