Embedded Microcontroller Interfacing (eBook)

Preface 5
Contents 8
Operational Amplifier and Analog Signal Processing Circuits: A Revision 13
Introduction 13
Voltage Follower Circuit 14
Inverting Amplifier 15
Sign Changer 15
Phase Shifter 16
Inverting Summing Amplifier 16
Non-inverting Amplifier 16
Non-inverting Summing Amplifier 17
Difference Amplifier 18
Current to Voltage (I-V) Converter 19
Integrator 19
Differentiator 21
Comparators and Schmitt Triggers 21
Logarithmic Amplifier 23
Exponential Amplifier 25
Single-Pole Filters 25
Double-Pole Filters 27
Band-Pass and Band-Stop Filters 28
Oscillator Circuits 30
Introduction to Silicon Labs C8051F020 Microcontroller 32
Introduction 32
CIP-51 32
C8051F020 System Overview 33
Memory Organization 35
Program Memory 35
Data Memory 36
Stack 36
Special Function Registers (SFRs) 37
I/O Ports and Crossbar 38
12-Bit Analog to Digital Converter 39
8-Bit Analog to Digital Converter 40
Digital to Analog Converters 41
Analog Voltage Comparators 43
Enable/Disable Comparator 44
Programmable Hysteresis 44
Comparator Output and Interrupt 45
Voltage Reference 46
REF0CN: Reference Control Register 47
Programmable Counter Array (PCA) 48
PCA Counter/Timer and Timebase Selection 49
Operation Modes and Interrupts 50
Edge-Triggered Capture Mode 52
Software Timer (Compare) Mode 53
High Speed Output Mode 53
Frequency Output Mode 54
8-Bit Pulse Width Modulator Mode 55
16-Bit Pulse Width Modulator Mode 57
C Programming for Silabs C8051F020 Microcontroller 59
Introduction 59
Register Definitions, Initialization and Startup Code 59
Basic C Program Structure 60
Programming Memory Models 60
Overriding the Default Memory Model 61
Bit-Valued Data 62
Special Function Registers 62
Locating Variables at Absolute Addresses 63
C Language Operators and Control Structures 63
Relational Operators 63
Logical Operators 64
Bitwise Logical Operators 64
Compound Operators 65
Making Choices 66
Repetition 67
Waiting for Events 68
Early Exits 68
Functions 69
Standard Function – Initializing System Clock 69
Memory Model Used for a Function 70
Interrupt Functions 70
Timer 3 Interrupt Service Routine 70
Disabling Interrupts before Initialization 71
Timer 3 Interrupt Initialization 71
Register Banks 72
Reentrant Functions 72
Pointers 73
A Generic Pointer in Keil$^TM$ C 73
Memory Specific Pointers 73
Summary of Data Types 74
Appendix 75
Design Issues of Microcontroller Interfacing 76
Introduction 76
Open-Collector Configuration 76
Protection of Microcontroller from Over-Voltage 77
Switching Inductive Load and Diode Protection 80
Potential Divider for Feedback Voltage 81
Interfacing a Digital Signal 84
Interfacing an Analog Signal 87
Discussions 90
Embedded Microcontroller Based DC Motor Control: A Project Based Approach 92
Introduction 92
Description of the Problem 93
Motivation of the Project 95
Basic Theory of the Project 96
Speed Control Using Pulse Width Modulation (PWM) 96
Generating PWM Signal 97
PWM Frequency: Timer 0 Reload Value 98
Varying the PWM Duty Ratio 99
Measuring Motor Speed and Closed Loop Control 100
Measuring Actual Motor Speed 100
Calculating the Value of K 101
Counting N (Number of Ticks for One Revolution) 101
Setting Motor Reference Speed 102
Recording Transient Behavior of Motor 102
Displaying Actual Motor Speed as an Analog Voltage on Oscilloscope 103
Guidelines to the Students 104
Outcome of the Project 108
Embedded Microcontroller Based Switched Mode Power Supply: A Student Project 112
Introduction 112
Description of the Project: Design of Power Supply 113
Specifications of the Problem 113
Objectives 113
Experiment and Comments 113
Guidance on the Implementation 114
Experiment with Open-Loop Power Circuit 114
Design and Implementation of the Control Circuit 114
Experiment with the Implemented Model 114
Submission Requirements 114
Design Process 115
Design of a Closed Loop Controller 117
Oscillator 117
Op Amp 118
Comparator 118
NAND Block 118
Power Circuit 118
Implementation of an Embedded Microcontroller Based Switched Mode Power Supply 121
Design Issues 125
Challenges of the Project Implementation 125
Conclusions 126
Appendix 126
Embedded Microcontroller Based Magnetic Levitation 136
Introduction 136
Background and Motivation 136
Hybrid Active Magnetic Bearing 138
Displacement Sensor 138
Permanent Magnet 138
Electromagnet and Force Relationship 140
Design of Control System 142
PID Controller 142
Analog Control System 143
Results from the Controller 146
Microcontroller Based Control System 150
Microcontroller Code 152
Results of the Microcontroller Based Control 155
Conclusions 157
Appendix 158
Embedded Microcontroller Based Fireworks Detonation System 165
Introduction 165
Preliminary Version of the System 166
Requirements 168
Design and Implementation 168
Overview of Control Software 168
Manual Interface 169
Scripting Interface 170
Designer Interface 172
Remote Firing Module 172
Overview and Methodology 172
Electric Matches 173
User Interface 174
Operational Modes 175
Wireless Network 176
Power Supply 176
Battery Charger 177
Firing and Testing 178
Central Control Circuit 179
LCD Control Circuit 180
RF Modem Control Circuit 181
IO Control Circuit 183
Developed Hardware 184
Firmware 187
Overview 187
Communications 188
Command and Response Set 189
Event System 190
Appendix 192
Embedded Microcontroller Based Non-destructive Seafood Inspection System 207
Introduction 207
Working Principle of Interdigital Sensors 207
Sensing System for Seafood Inspection 211
Interfacing to Microcontroller 212
Initialization of Important Parts of Microcontroller 212
Electronics and Signal Processing Circuit for the Low Cost Sensing System 215
Smooth Sine Wave Generation 217
Signal Rectification and Amplification 218
Calibration, Sensitivity Threshold and Signal Definitions 218
Prototype of Seafood Inspection Tool (SIT) 220
Conclusion 221