Microchip Technology MCP355X Sensor Application Developer’s Board User guide

MCP355X
Sensor Application
Developer’s Board
User’s Guide
© 2006 Microchip Technology Inc. DS51609A
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8-bit MCUs, KEELOQ
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code hopping devices, Serial
DS51609A-page ii © 2006 Microchip Technology Inc.
MCP355X SENSOR APPLICATION
DEVELOPER’S BOARD USER’S GUIDE
Table of Contents
Preface ........................................................................................................................... 1
Introduction............................................................................................................ 1
Document Layout .................................................................................................. 1
Conventions Used in this Guide ............................................................................ 2
Recommended Reading........................................................................................ 2
The Microchip Web Site ........................................................................................ 3
Customer Support ................................................................................................. 3
Document Revision History ................................................................................... 3
Chapter 1. Product Overview ....................................................................................... 5
1.1 Introduction ..................................................................................................... 5
1.2 What is the MCP355X Sensor Application Developer’s Board? .................... 5
1.3 What the MCP355X Sensor Application Developer’s Board Kit Includes ...... 6
Chapter 2. Hardware Description ................................................................................ 7
2.1 Overview ........................................................................................................ 7
2.2 Sensor Input Connections .............................................................................. 8
2.3 Channel 1 - Low-Cost Differential Gain Circuit Using MCP6XX Amplifier ...... 9
2.4 Channel 2 - High-Precision Gain Circuit ....................................................... 11
2.5 Bridge Simulator Boards .............................................................................. 12
Chapter 3. Firmware Description ............................................................................... 13
3.1 Firmware Overview ...................................................................................... 13
3.2 PIC16F877 ................................................................................................... 13
3.3 PIC18F4550 ................................................................................................. 16
Chapter 4. DataView .................................................................................................... 17
4.1 Overview ...................................................................................................... 17
4.2 Scope Plot Window ...................................................................................... 17
4.3 Noise Histogram Window ............................................................................. 18
4.4 Auxiliary Data Window ................................................................................. 18
4.5 Configuring DataView ................................................................................... 19
© 2006 Microchip Technology Inc. DS51609A-page iii
MCP355X Sensor Application Developer’s Board User’s Guide
Appendix A. Schematic and Layouts ........................................................................21
A.1 Introduction .................................................................................................. 21
A.2 Schematic - Page 1 .................................................................................... 22
A.3 Schematic - Page 2 .................................................................................... 23
A.4 Schematic - Page 3 .................................................................................... 24
A.5 Schematic - Bridge Simulator ..................................................................... 25
A.6 Board Layout - Top Layer and Silk Screen .............................................. 26
A.7 Board Layout - Top Layer .......................................................................... 26
A.8 Board Layout - Bottom Layer and Silk Screen ......................................... 27
A.9 Board Layout - Bottom Layer ..................................................................... 27
A.10 Board Layout - Bridge Simulator .............................................................. 28
Appendix B. Bill Of Materials (BOM) ..........................................................................29
Worldwide Sales and Service .....................................................................................32
DS51609A-page iv © 2006 Microchip Technology Inc.
MCP355X SENSOR APPLICATION
DEVELOPER’S 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 MCP355X Sensor Application Developer’s 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 MCP355X Sensor Application Developer’s Board as a development tool. The manual layout is as follows:
Chapter 1. “Product Overview” – Important information about the MCP355X Sensor Application Developer’s Board.
Chapter 2. “Hardware Description”– Includes detailed description of the hardware for the MCP355X Sensor Application Developer’s Board.
Chapter 3. “Firmware Description” – Includes detailed description of the software for the MCP355X Sensor Application Developer’s Board.
Chapter 4. “DataView” - Includes detail description of the DataView software.
Appendix A. “Schematic and Layouts” – Shows the schematic and layout diagrams for the MCP355X Sensor Application Developer’s Board.
Appendix B. “Bill Of Materials (BOM)” – Lists the parts used to build the MCP355X Sensor Application Developer’s Board
© 2006 Microchip Technology Inc. DS51609A-page 1
MCP355X Sensor Application Developer’s 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® 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
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) { ... }

RECOMMENDED READING

This user's guide describes how to use MCP355X Sensor Application Developer’s Board. The following Microchip documents are available and recommended as supplemental reference resources.
MCP3550/1/3 Data Sheet, “Low-Power Single Channel 22-Bit Delta-Sigma ADCs” (DS21950)
This data sheet provides detailed information regarding the MCP3550/1/3 device.
AN1007, “Designing With The MCP3551 Delta Sigma ADC” (DS01007)
This application note documents the design decisions associated with this device.
DS51609A-page 2 © 2006 Microchip Technology Inc.

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 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
Preface

DOCUMENT REVISION HISTORY

Revision A (June 2006)
• Initial Release of this Document.
© 2006 Microchip Technology Inc. DS51609A-page 3
MCP355X Sensor Application Developer’s Board User’s Guide
NOTES:
DS51609A-page 4 © 2006 Microchip Technology Inc.
MCP355X SENSOR APPLICATION
DEVELOPER’S BOARD USER’S GUIDE

Chapter 1. Product Overview

1.1 INTRODUCTION

This chapter provides an overview of the MCP355X Sensor Application Developer’s Board and covers the following topics:
• What is the MCP355X Sensor Application Developer’s Board?
• What the MCP355X Sensor Application Developer’s Board Kit includes

1.2 WHAT IS THE MCP355X SENSOR APPLICATION DEVELOPER’S BOARD?

The MCP355X Sensor Application Developer’s Board allows for easy system design of high resolution systems such as weigh scale, temperature sensing, or other small signal systems requiring precise signal conditioning circuits. The reference design includes firmware that performs all the necessary functions including ADC sampling, USB communication for PC data analysis, LCD display output, zero cancellation, full scale calibration, and units display in gram (g), kilogram (kg), or ADC output units. Figure 1-1 shows the LCD display output in kg of a high resolution system.
.
FIGURE 1-1: MCP355X Sensor Application Developer’s Board LCD showing weigh scale output in kilograms.
Reference Design Features:
• Signal Conditioning Circuit Selection and Gain Selection
• Voltage Reference Selection
•PICmicro
• Preprogrammed LCD firmware for ADC Output in g, kg or system code
• DataView USB connection for easy PC evaluation of system error
• High Resolution System Board Design
© 2006 Microchip Technology Inc. DS51609A-page 5
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microcontroller sockets and LCD for firmware development on-board
MCP355X Sensor Application Developer’s Board User’s Guide

1.3 WHAT THE MCP355X SENSOR APPLICATION DEVELOPER’S BOARD KIT INCLUDES

This MCP355X Sensor Application Developer’s Board Kit includes:
• The MCP355X Sensor Application Developer’s Board, 102-00090
• MCP355X Sensor Application Developer’s Board User’s Guide (DS-51609)
• MCP3550/1/3 Data Sheet, “Low-Power Single Channel 22-Bit Delta Sigma ADCs” (DS21950)
• AN1030, “Weigh Scale Applications for the MCP3551” (DS01030)
DS51609A-page 6 © 2006 Microchip Technology Inc.

2.1 OVERVIEW

The MCP355X Sensor Application Developer’s Board’s purpose is to ease develop­ment of small signal sensor MCP355X applications such as weigh scales. There are two circuits, or channels, to allow for comparison of different approaches to signal conditioning circuits. The first channel is a low-cost, low-power signal conditioning circuit that uses Microchip’s MCP6XX amplifiers. This circuit is intended to be a reference design for low power, low cost MCP355X applications requiring intermediate ranges of signal gain.
The second channel uses a precision amplifier with high gain. It is intended to be a reference design for MCP355X circuits that can require higher resolution.
The board has jumper connections and screw terminals to connect external sensors such as load cells or RTD temperature sensors. The board easily accomodates both 4-wire and 6-wire load cells sensor connections.
The system includes two PICmicro MCUs for firmware development and data analysis through either an LCD display or graphically on a PC using a USB connection. A PIC16F877 communicates with the two MCP355X channels, push-buttons and LCD display.
For data analysis on the PC the USB PIC18F4550 is used. This device collects the post processed PIC16F877 data and passes it via USB to the PC for display on DataView software.
MCP355X SENSOR APPLICATION
DEVELOPER’S BOARD USER’S GUIDE

Chapter 2. Hardware Description

USB to PC running DataView
PIC18F4550
C
2
I
PIC16F877
FIGURE 2-1: MCP355X Sensor Application Developer’s Board Functional Block Diagram and Results.
© 2006 Microchip Technology Inc. DS51609A-page 7
8
3
MCP3551 ΔΣ
4
SPI
MCP3551 ΔΣ
LCD Display
Push Button Control Switches
ADC
CHANNEL 1
ADC
CHANNEL 2
GAIN
GAIN
Sensor Input Connections
+ 25 hidden pages