Microcontroller-Based Temperature Monitoring and Control is an essential and practical guide for all engineers involved in the use of microcontrollers in measurement and control systems. The book provides design principles and application case studies backed up with sufficient control theory and electronics to develop your own systems. It will also prove invaluable for students and experimenters seeking real-world project work involving the use of a microcontroller. A basic mathematical and engineering background is assumed, but the use of microcontrollers is introduced from first principles.

Techniques for the application of microcontroller-based control systems are backed up with the basic theory and mathematics used in these designs, and various digital control techniques are discussed with reference to digital sample theory. Author Dogan Ibrahim has used his engineering experience to write a book based on real-world applications.

The first part of the book covers temperature sensors and their use in measurement, and includes the latest non-invasive and digital sensor types. The second part covers sampling procedures, control systems and the application of digital control algorithms using a microcontroller. The final chapter describes a complete microcontroller-based temperature control system, including a full software listing for the programming of the controller.

Table of Contents

Preface

Microcomputer Systems

Introduction

Microcontroller systems

Microcontroller features

Microcontroller architectures

The PIC microcontroller family

Minimum PIC configuration

PIC16F84 microcontroller

• Pin configuration
• OPTION_REG register
• INTCON register
• TRISA and PORTA registers
• TRISB and PORTB registers
• Timer module and TMR0 register

PIC16F877 microcontroller

• Pin configuration

Using C language to program PIC microcontrollers

• FED C compiler variables
• Comments in programs
• Arrays
• Constants
• Enumerated constants
• Operators
• Program control in FED C
• Header files
• PIC PORT commands
• Built-in functions
• Using a LCD display
• Structures
• Unions
• User functions
• Pointers
• The pre-processor

PIC C project development tools

Structure of a microcontroller based C program

Program Description Language

• START-END
• Sequencing
• IF-THEN-ELSE-ENDIF
• DO-ENDDO
• REPEAT-UNTIL
• SELECT

Example LCD project

Exercises

Further reading

Temperature and its Measurement

Temperature scales

Types of temperature sensors

Measurement errors

• Calibration errors
• Sensor self heating
• Electrical noise
• Mechanical stress
• Thermal coupling
• Sensor time constant
• Sensor leads

Selecting a temperature sensor

Thermocouple Temperature Sensors

Thermocouple types

Thermocouple junction mounting

Thermocouple insulation

• Standard insulating materials
• Mineral insulated thermocouples

Extension cables

Thermocouple response times

Thermocouple styles

Thermocouple temperature voltage relationships

• Using thermocouple reference tables
• Using power series method
• Using linear approximation

The theory of the cold junction compensation

Microcontroller based practical thermocouple circuits

PROJECT--Measuring temperature using a thermocouple and a microcontroller

• The specifications
• The hardware design
• The software design

Exercises

RTD Temperature Sensors

RTD principles

RTD types

RTD temperature resistance relationship

RTD standards

• Class A standard
• Class B standard

Practical RTD circuits

• Simple current source circuit
• Simple voltage source circuit
• Four-wire RTD measurement
• Simple RTD bridge circuit
• Three-wire RTD bridge circuit

Microcontroller based RTD temperature measurement

PROJECT--Designing a microcontroller based temperature measurement system using an RTD

• Specifications
• Design
• The circuit diagram
• Operation of the circuit
• Program listing

Exercises

Thermistor Temperature Sensors

Thermistor principles

Thermistor types

Self-heating

Thermal time constant

Thermistor temperature-resistance relationship

• Temperature-resistance table
• Steinhart-Hart equation
• Using temperature-resistance characteristic formula
• Thermistor linearization

Practical thermistor circuits

• Constant current circuit
• Constant voltage circuit
• Bridge circuit
• Non-inverting operational amplifier circuit
• Inverting operational amplifier circuit

Microcontroller based temperature measurement

PROJECT--Designing a microcontroller based temperature measurement system using a thermistor

• Specifications
• Design
• The circuit diagram
• Operation of the circuit
• Program listing

Exercises

Integrated Circuit Temperature Sensors

Voltage output temperature sensors

• Application of voltage output temperature sensors

Current output temperature sensors

• Applications of current output temperature sensors

Digital output temperature sensors

• Applications of digital output temperature sensors

PROJECT--Using a digital output sensor to measure the temperature

• The hardware
• The software

Exercises

Digital Control Systems and the z-transform

The sampling process

The z-transform

• Properties of the z-transform
• z-transform from the Laplace transform

Inverse z-transform

• Power series method
• Partial fraction expansion method

The pulse transfer function

• Open-loop digital control systems
• Open-loop time response
• Closed-loop control systems
• Closed-loop time response

Exercises

Stability

Jury's stability test for small systems

The root-locus technique

Digital control algorithms

Temperature control using digital computers

• Bang-bang control of temperature
• Control of temperature using continuously variable controller
• Ziegler-Nichols PID tuning algorithm

Digital realizations

• Direct programming
• Serial programming
• Parallel programming
• Canonical programming

Realization of the discrete PID controller

Problems with the standard PID controller

Choosing a sampling interval

Exercises

Case Study: Temperature Control Project

Overview

The mathematical model

• Mathematical model of the tank
• Mathematical model of the heater
• Mathematical model of the temperature sensor

The circuit diagram

Identification of the system

Pulse width output of the microcontroller

Design of a PI controller

• The software of the PI controller
• Results

Design of a PID controller

• The software of the PID controller
• Results

Compensating for heat losses

Other considerations

Exercises

Appendix A: Platinum RTD Sensor Resistances (α = 0.00385)

Appendix B: ASCII Code

Appendix C: FED C Compiler Library Functions

Glossary

Index

Paperback; 256 pages