Microchip Technology MCP3901, PIC18F65J90 User Manual

MCP3901 and PIC18F65J90

Energy Meter Reference Design

User’s Guide

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PIC

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Printed on recycled paper.

ISBN: 978-1-61341-960-1

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MCUs and dsPIC® DSCs, KEELOQ

code hopping

MCP3901 AND PIC18F65J90

ENERGY METER

REFERENCE DESIGN

Preface ...........................................................................................................................7

Introduction............................................................................................................7

Document Layout .................................................................................................. 8

Conventions Used in this Guide............................................................................ 9

Recommended Reading.............................................................. .. ......................10

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

Customer Support.................... .................................... .................. .....................10

Document Revision History................................................................................. 10

Chapter 1. Product Overview

1.1 Introduction ...................................................................................................11

1.2 What the MCP3901 and PIC18F65J90 Energy Meter

Reference Design Kit Includes ............................................................... 12

1.3 Getting Sta rted .... .................................................................................. ....... 12

Chapter 2. Hardware

2.1 Overview ............. ......................................................................................... 13

2.2 Input and Analog Front End .........................................................................16

Chapter 3. Calculation Engine and Register Description

3.1 Calculati on E n g in e Si g nal Flow Summary ................................................... 17

3.2 Register L is t ................................................................................................. 18

3.3 MODE .......................................................................................................... . 19

3.4 STATUS .......... .. ........................................................................................... 20

3.5 CAL_CONT R O L ........................................................................................... 20

3.6 LINE_CYC ................. .. ................................................................................ 21

3.7 LINE_CYC _ C N T ............. ... ..................................................... .. .. ................ 2 1

3.8 RAW2_I_RMS ..............................................................................................21

3.9 RAW_I_RM S .................... .......................................... .................................. 22

3.10 I_RMS ............... ......................................................................................... 22

3.11 RAW2_V _ R M S ......................................................................................... 22

3.12 RAW_V_ R M S .......................... ........................................................ ......... 22

3.13 V_RMS ....... ... .. ........................................................................................... 22

3.14 LINE_F R E Q UE N CY ............................................... .................................... 23

3.15 RAW_PO WER_ACT ......................................... ........................................ 23

3.16 POWER_ A CT ..................................... .......................................... .............. 23

3.17 POWER_APP ............................................................................................23

3.18 RAW_PO WER_REACT .......... ................ ................................................... 24

3.19 POWER_ R EA CT ...... .. .. ............................. .......................................... ....... 24

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

3.20 PERIOD .... ....................................................... ........................................... 24

3.21 ENERG Y _ AC T ............. .. ............................ ................................................ 24

3.22 ENERGY_APP ..........................................................................................25

3.23 I_ABS_MAX ...............................................................................................25

3.24 V_ABS _ M A X ............. ... .............................................................................. 2 5

3.25 ENERG Y _ RE A C T ...................................................................................... 25

3.26 PHASE_COMPENSATION ........................................................................ 25

3.27 OFFSE T _ I_ R M S .. .. .................................................................................. . 26

3.28 OFFS ET _ V _RMS . .. ..................................................... .. ... ......................... 2 6

3.29 GAIN_I_RMS ............................................................................................. 26

3.30 GAIN_V _ R MS ............................................................................................ 26

3.31 OFFSE T _ P O WE R _ A CT .................... ...................................................... 26

3.32 GAIN_P O WER_ACT ........ .. ........................................................................ 27

3.33 OFFSE T _ P O WE R _ RE ACT .............. ........................................................ 27

3.34 GAIN_P O WER_REACT ... .................................................................... ...... 27

3.35 GAIN_E N E RGY_ACT ................................................................................ 27

3.36 GAIN_ENERGY_APP ................................................................................ 27

3.37 GAIN_E N E RGY_REACT . .. .. ...................................................................... 27

3.38 CF_PU LSE_WIDTH ............. ...................................................................... 28

3.39 GAIN_D E N R_ENERGY_A C T ......... ................ ........................................... 28

3.40 GAIN_N U MR_ENERGY_ A CT ............................................ ....................... 28

3.41 MODE1 _ D EF ............................................................. .............................. 28

3.42 CAL_ST A T US ........... ... .......................... .. .. ................................................ 28

3.43 MAXIMUM CURRENT ............................................................................. 29

3.44 CALIB R AT ION_VOLTAG E ....... .. ..................................................... .. ... ... 29

3.45 CALIBRATION_CURRENT ......................................................................29

3.46 CALIB R AT ION_FREQUE N CY . ................................................................. 29

3.47 METER _ C ON S T A N T ......................................... ....................................... 2 9

3.48 CALIB R A T I O N _ L INE _ C Y CLE ................................................. ... .. ............ 30

3.49 GAIN_D E N R_ENERGY_R EA C T ............ .. ... ............................................. 30

3.50 GAIN_N U MR_ENERGY_ R E ACT ............. ................................................ 30

3.51 PHASE_COMPENSATION_90 ................................................................. 30

3.52 CREEP_THRSHOLD_MINUTE ................................................................. 30

3.53 CREEP_THRSHOLD_SECOND ................................................................30

Chapter 4. Meter Protocol and Timings

4.1 Protocol ..................................................... .. ... ............................................. 31

Appendix A. Schematic and Layouts

A.1 Introduction .................................................................................................. 33

A.2 Schematics and PCB Layout ........................ ......................... .. .. ..................33

A.3 Board – ADC Schematic ............................................................................. 34

A.4 Board – MCU S c he matic ........... .. ............. .. ... ............................................. 35

A.5 Board – LCD and USB Schematic .............. .. ............................... ................36

A.6 Board – Top Silk and Pads ........................ .. ..................... .......................... 37

A.7 Board – Top Copper .................................................................................... 38

A.8 Board – Bottom Copper ...............................................................................39

A.9 Board – Bottom Silk and Pads ..................... .. .. .. ............................. .. ...........40

A.10 Board – To p 3 D ............................................................. .. .. ............. ... .. ....... 41

A.11 Board – Bo tt om 3D ...... ............. ... .. ............. .. .. ........................... .. .. ............ 42

Appendix B. Bill of Materials (BOM)

Worldwide Sales and Service ....................................................................................46

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

MCP3901 AND PIC18F65J90

ENERGY METER

REFERENCE DESIGN

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 p age 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.

IDE online help.

INTRODUCTION

This chapter contains general information that will be useful to know before using the MCP3901 and PIC18F65J90 Energy Meter Reference Design User’s Guide. Items discussed in this chapter include:

• Document Layout

• Conventions Used in this Guide

• Recommended Reading

• The Microchip Web Site

• Customer Support

• Document Revision History

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

DOCUMENT LAYOUT

This document describes how to use the MCP3901 and PIC18F65J90 Energy Meter Reference Design as a development tool to emulate and debug firmware on a target board. The manual layout is as follows:

• Chapter 1. “Product Overview” – Important information on using the MCP3901

and PIC18F65J90 Energy Meter Reference Design including a Getting Started section that describes wiring the line and load connections.

• Chapter 2. “Hardwa re ” – Includes details on the function blocks of the meter

including the analog front end design, phase lock loop circuitry, and power supply design.

• Chapter 3. “Calculation Engine and Register Description” – This section

describes the digital signal flow for all power output quantities such as RMS current, RMS voltage, active power, and apparent power. This section also includes the calibration register’s detail.

• Chapter 4. “Meter Protocol and Timings”– This chapter describes the protocol

used for accessing the registers, including commands that are used to interface to the meter.

• Appendix A. “Schematic and Layouts” – Shows the schematic and layout

diagrams.

• Appendix B. “Bill of Materials (BOM)” – Lists the parts used to build the

MCP3901 and PIC18F65J90 Energy Meter Reference Design.

CONVENTIONS USED IN THIS GUIDE

This manual uses the following docum entat io n conven tion s:

DOCUMENTATION CONVENTIONS

Description Represents Examples

Arial font:

Italic chara c ters Referenced books MPLAB

Initial caps A window the Output window

Quotes A field name in a window or

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 r epeated text var_name [,

Preface

IDE User’s Guide

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

A dialog the Settings dialog A menu selection select Enable Programmer

“Save project before build”

dialog A menu path File>Save

A tab Click the Power tab

4‘b0010, 2‘hF1 where N is the tota l number of digits, R is th e radi x 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’

any valid filename

[options]

Choice of mut ually exclus ive arguments; an OR selection

Represents code supplied by user

errorlevel {0|1}

var_name...]

void main (void)

{ ...

}

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

DOCUMENT REVISION HISTORY

Revision A (January 2012)

• Initial Release of this Document.

Chapter 1. Product Overview

1.1 INTRODUCTION

The MCP3901 and PIC18F65J90 Energy Meter Reference Design is a fully functional IEC Class 0.5 compliant single-phase meter. This low-cost design does not use any transformers and requires few external components. The PIC18F65J90 directly drives the LCD, and includes both an isolated USB connection for meter calibration and access to the device power calculations. The system calculates active energy, active power, RMS current, RMS voltage, reactive energy, reactive power, apparent power and other typical power quantities.

The Microchip Energy Meter 1-Phase Software is used to calibrate and monitor the system, and can be used to create custom calibration setups. For some accuracy requirements, only a single point calibration may be needed. The energy meter software offers an automated step-by-step calibration process that can be used to quickly calibrate energy meters.

MCP3901 AND PIC18F65J90

ENERGY METER

REFERENCE DESIGN

FIGURE 1-1: MCP3901 and PIC18F65J90 Single-Phase Energy Meter.

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

1.2 WHAT THE MCP3901 AND PIC18F65J90 ENERGY METER REFERENCE DESIGN KIT INCLUDES

This MCP3901 and PIC18F65J90 Energy Meter Reference Design kit includes:

• MCP3901 and PIC18F65J90 Energy Meter Reference Design User’s Guide

• Important Information Sheet

1.3 GETTING STARTED

To describe how to use the MCP3901 and PIC18F65J90 Energy Meter Reference Design, the following example is given using a two-wire 1-phase, 220 V AC line voltage and connections using energy meter calibrator equipment, or other programmable load source. The meter design uses a 5A load for calibration current, and a maximum current (I

To test a calibrated meter, the following connections apply for a two-wire connection.

1.3.1 Step 1: Wiring Connections

Figure 1-2 identifies the line and load connections of the MCP3901 and PIC18F65J90 Energy Meter Reference Design.

MAX

) of 60A.

Line

Neutral

MAIN

Line

Neutral

LOAD

FIGURE 1-2: Example Connections using a 2-Wire System.

1.3.2 Step 2: Turn On Line/Load Power to the Meter (Power the Meter)

The meter will turn on when the line connection has 220V connected. The LCD display will show the total energy accumulated.

2.1 OVERVIEW

Figures 2-1 and 2-2 show the MCP3901 and PIC18F65J90 and Energy Meter

Reference Design:

MCP3901 AND PIC18F65J90

ENERGY METER

REFERENCE DESIGN

Chapter 2. Hardware

LCD1

D9D8

SW3

SW1

C40

SW2

DANGER

HIGH VOLTAGE

MCP3901 / PIC18F65J90 SHUNT METER

Legend:

1 = IR for meter communication 7 = Push button Switches 2 = Test points 8 = 9-digit LCD Disp lay with icons for kWh and kVARh 3 = MCP3901 Analog Front End 9 = Pulse Output for Active and Reactive

4 = +9V DC Input (non-isolated) 10 = USB Connection (isolated) 5 = Connections to shunt

current sensing resistor

6 = Connections to Line and Neutral

(isolated)

FIGURE 2-1: Top View – Hardware Components.

MCP3901 and PIC18F65J90 Energy Meter Reference De sign

C40

R21 R20

R28

R27 R26

C32

C24 C25

R19

R17

R29

C39

R33

C37

R30

R34

DANGER

HIGH VOLTAGE

C41

R14 R12 C2

R15 R11 C1

C38

C30 C27 C21 C22

C10

R31 C23

R24 R25

C19

C17

R18

C16

MOV1

R32

Legend:

12 = Opto-isolators for Pulse outputs 13 = Power supply 14 = Non-volatile memory for calibration constants and energy usage data 15 = PIC18F65J90 16 = Isolation IC 17 = MCP2200 for USB connection

FIGURE 2-2: Bottom View – Hardware Components.

Hardware

PIC18F65J90

RA2

RA3 RG1

RG4

RC7/RX RC6/TX

RA5

RC3/SCK

RC4/SDI

RC5/SDO

RA1

SWITCH SWITCH

USB to UART

Converter

MCP2200

Active Power

Mini - USB Connector

(ISOLATED)

SCK

SDO

SDI CS

MCP3901

AFE

SCK

SDO

SDI CS

Reactive Power

FIGURE 2-3: Digital Connections.

25LC256

SPI - EEPROM

+ 32 hidden pages

Microchip Technology MCP3901, PIC18F65J90 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Trademarks

Table of Contents

Preface

DOCUMENT REVISION HISTORY

Chapter 1. Product Overview

1.1 INTRODUCTION

1.2 WHAT THE MCP3901 AND PIC18F65J90 ENERGY METER REFERENCE DESIGN KIT INCLUDES

1.3 GETTING STARTED

2.1 OVERVIEW

Chapter 2. Hardware