Microchip Technology Humidity Sensor PICtail, PIC16F690DM-PCTLHS User Manual

Humidity Sensor

PICtail™ Demo Board

User’s Guide

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HUMIDITY SENSOR PICTAIL™

DEMO BOARD USER’S GUIDE

Table of Contents

Preface ........................................................................................................................... 1

Introduction............................................................................................................ 1

Document Layout .................................................................................................. 1

Conventions Used in this Guide ............................................................................ 2

Recommended Reading........................................................................................ 3

The Microchip Web Site ........................................................................................ 4

Customer Support ................................................................................................. 4

Document Revision History ................................................................................... 4

Chapter 1. Product Overview

1.1 Introduction ..................................................................................................... 5

1.2 Kit Contents .................................................................................................... 5

1.3 Humidity Sensor PICtail™ Demo Board ......................................................... 5

1.4 Associated Tools ............................................................................................ 7

1.5 Assembly Code Modules ................................................................................ 8

Chapter 2. Setup and Installation

2.1 Introduction ..................................................................................................... 9

2.2 Required Tools ............................................................................................... 9

2.3 Setting up the Humidity Sensor PICtail™ Demo Board ................................. 9

2.4 Connecting to Alternate Tools ...................................................................... 11

Chapter 3. Operation

3.1 Introduction ................................................................................................... 13

3.2 Configuring the Humidity Sensor PICtail™ Demo Board ............................. 13

3.3 Using the Humidity Sensor PC Program ...................................................... 13

3.4 Humidity Sensor Calibration ......................................................................... 15

Chapter 4. Modified Circuit

4.1 Introduction ................................................................................................... 17

4.2 The “Reduced Current” Circuit ..................................................................... 17

Humidity Sensor PICtail™ Demo Board User’s Guide

Appendix A. Schematic and Layouts

A.1 Introduction .................................................................................................. 19

A.2 Highlights ..................................................................................................... 19

A.3 Demonstration Board Description ................................................................ 19

A.4 The “Reduced Current” Modification ............................................................ 20

A.5 Additional Comments ................................................................................... 20

Appendix B. Bill Of Materials (BOM)

B.1 Humidity Sensor PICtail™ Demo Board BOM ............................................. 25

B.2 BOM for Humidity Sensor and Other Capacitors in Box .............................. 26

B.3 BOM for “Reduced Current” Modifications ................................................... 26

Worldwide Sales and Service .....................................................................................28

HUMIDITY SENSOR PICTAIL™

DEMO BOARD 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.

INTRODUCTION

This chapter contains general information that will be useful to know before using the Humidity Sensor PICtail™ Demo Board. Items discussed in this chapter include:

• Document Layout

• Conventions Used in this Guide

• Recommended Reading

• The Microchip Web Site

• Customer Support

• Document Revision History

DOCUMENT LAYOUT

This document describes how to use the Humidity Sensor PICtail™ Demo Board as a development tool to emulate and debug firmware on a target board. The manual layout is as follows:

• Chapter 1. “Product Overview” – This is an introduction to the Humidity Sensor

PICtail™ Demo Board. It covers the kit contents, associated tools and how they work together.

• Chapter 2. “Setup and Installation” – Covers the initial set-up of the Humidity

Sensor PICtail™ Demo Board. It lists the required tools, shows how to connect this board and demonstates how to verify the set-up.

• Chapter 3. “Operation” – This chapter discusses using the humidity sensor on

the PCB and using the software PC Application.

• Chapter 4. “Modified Circuit” – Gives the modifications necessary to increase

measurement resolution by a factor of 100 (see AN1016 for details)

• Appendix A. “Schematic and Layouts” – Gives detailed information on the

Humidity Sensor PICtail™ Demo Board. Includes detailed circuit explanation, schematic and board layouts.

• Appendix B. “Bill Of Materials (BOM)” – Gives detailed information on the

Humidity Sensor PICtail™ Demo Board’s firmware.

Humidity Sensor PICtail™ Demo Board User’s Guide

CONVENTIONS USED IN THIS GUIDE

This manual uses the following documentation conventions:

DOCUMENTATION CONVENTIONS

Description Represents Examples

Arial font:

Italic characters Referenced books MPLAB

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

N‘Rnnnn A number in verilog format,

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

where N is the total number of digits, R is the radix and n is a digit.

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”

4‘b0010, 2‘hF1

any valid filename

[options] errorlevel {0|1}

var_name...] void main (void)

{ ... }

IDE User’s Guide

RECOMMENDED READING

This user's guide describes how to use Humidity Sensor PICtail™ Demo Board. Other useful documents are listed below and are recommended as supplemental reference resources.

PICkit™ 2 Microcontroller Programmer User’s Guide (DS51553)

Contains instructions on how to use the PICkit 2 Microcontroller Programmer hardware and software.

PICkit™ 1 Flash Starter Kit User’s Guide (DS40051)

Contains instructions on how to use the PICkit 1 Flash Starter Kit hardware and software.

MPLAB

This user’s guide covers Microchip’s low cost, real-time debugger and programmer for selected PICmicro (DSCs).

AN1016, “Detecting Small Capacitive Sensors Using the MCP6291 and PIC16F690 Devices” (DS01016)

Explains the functionality and design of this board’s circuit. Contains measurement results.

MCP6291/2/3/4/5 Data Sheet (DS21812)

Gives detailed information on the MCP6291/2/3/4/5 Op Amps.

PIC16F685/687/689/690 Data Sheet (DS41262)

Gives detailed information on the microcontroller used on the Humidity Sensor PICtail™ Demo Board.

PIC16C745/765 Data Sheet (DS41124)

Gives detailed information on the PICmicro microcontroller used on the PICkit 1 Flash Starter Kit.

ICD 2 In-Circuit Debugger User’s Guide (DS51331)

Preface

Microcontrollers (MCUs) and dsPIC® Digital Signal Controllers

The following document is available on the internet from the company listed, and is recommended as a supplemental reference resource.

Humirel, “Relative Humidity Sensor HS1100LF / HS1101LF,” Data Sheet, Rev. C, Sept. 2004.

Gives detailed information on Humirel’s (www.humirel.com) HS1101LF capacitive relative humidity sensor.

Humidity Sensor PICtail™ Demo Board User’s Guide

THE MICROCHIP WEB SITE

Microchip provides online support via 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

CUSTOMER SUPPORT

Users of Microchip products can receive assistance through several channels:

• Distributor or Representative

• Local Sales Office

• Field Application Engineer (FAE)

• Technical Support

• Development Systems Information Line Customers should contact their distributor, representative or field application engineer

(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 the web site at: http://support.microchip.com

DOCUMENT REVISION HISTORY

Revision A (December 2005)

• Initial Release of this Document.

Chapter 1. Product Overview

1.1 INTRODUCTION

The Printed Circuit Board (PCB) discussed in this user’s guide is described as follows:

HUMIDITY SENSOR PICTAIL™

DEMO BOARD USER’S GUIDE

• Order Number:

• Assembly Number:

•Board Name: This board supports the capacitive humidity sensor application note AN1016. It

measures the capacitance of a relative humidity sensor (or capacitor) plugged into the board. The on-board microcontroller sends the measured and calculated data to a PC (Personal Computer) for display.

Items discussed in this chapter include:

• Kit Contents

• Humidity Sensor PICtail™ Demo Board

• Associated Tools

• Initial Set-up

1.2 KIT CONTENTS

• Humidity Sensor PICtail™ Demo Board – This is an assembled and tested Printed Circuit Board (PCB).

• CD-ROM – Provided separately in the shipping box; it contains the files and literature mentioned in this user’s guide.

• Humidity Sensor (HS1101LF) – Provided separately in the shipping box.

• Bag of Capacitors – Provided separately in the shipping box. These capacitors are provided for the user’s convenience; they make it easy to try out this board’s functionality, and to verify its accuracy.

PIC16F690DM-PCTLHS 102-00084R1 Humidity Sensor PICtail™ Demo Board

1.3 HUMIDITY SENSOR PICTAIL™ DEMO BOARD

The circuit operation is detailed in AN1016, “Detecting Small Capacitive Sensors Using the MCP6291 and PIC16F690 Devices” (DS01016)

The Humidity Sensor PICtail™ Demo Board contains the circuitry represented in Figure 1-1. The ambient relative humidity changes the capacitance of the humidity sensor (HS1101LF from Humirel). This sensor is connected to a MCP6291 op amp and a resistor to form an inverting (Miller) integrator. The PIC16F690 microcontroller sends a square wave to the input of the integrator, which the integrator converts to a triangle wave at its output. The firmware controls the magnitude of the triangle wave and measures the integration time. The microcontroller measures the time it takes for the triangle wave to rise and fall. These times are converted to a capacitance value.

A 14-pin header is provided for connecting to the PICkit™ 1 Flash Starter Kit, which acts like a docking station. It includes a two-wire serial bus that transfers the data, and two more wires for board power (+5V and GND inputs). This interface also supports programming of the on-board PIC16F690.

Humidity Sensor PICtail™ Demo Board User’s Guide

The +5V single supply voltage from the PICkit™ 1 Flash Starter Kit board is bypassed with two bulk 1 μF capacitors near the header, and two local 0.1 μF capacitors (one for each Integrated Circuit (IC)).

A 6-pin header for ICSP™ (In-Circuit Serial Programming™) is available as an alternate interface for programming the on-board PIC16F690. This allows the user to modify the program that comes with the Humidity Sensor PICtail™ Demo Board (with the MPLAB ICD 2 or PICkit™ 2 microcontroller programmer).

Humidity Sensor

PICtail™ Demo Board

Ambient

Humidity

Sensor

Tes t P oin ts

+5V

GND

Vsen

Vcm

Vint

Op Amp

MCP6291

N.C.

Microcontroller

PIC16F690

+5V

GND

to PICkit™ 1 Flash Starter Kit

ICSP™

FIGURE 1-1: Humidity Sensor PICtail™ Demo Board Block Diagram.

The test points make it easier to test key points in the circuit using common lab equipment. The test points are:

• GND – Is connected to ground plane, and is for any lab equipment

• +5V – Positive supply voltage (at board edge); it provides a means to power this board with a laboratory power supply (when not connected to the PICkit™ 1 Flash Starter Kit)

•V

INT – Integrator’s input (a square wave during measurements) CM – Op amp’s common mode voltage (at its inverting input)

•V

SEN – Integrator’s output of the integrator (a triangle wave during

measurements)

More details on the circuit and on its design can be found in Appendix A. “Schematic and Layouts” and AN1016, “Detecting Small Capacitive Sensors Using the MCP6291 and PIC16F690 Devices” (DS01016).

+ 22 hidden pages

Microchip Technology Humidity Sensor PICtail, PIC16F690DM-PCTLHS User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual