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Building Embedded Systems
Programmable Hardware
Changyi Gu
Building Embedded Systems
Changyi Gu San DiegoCalifornia, USA
ISBN-13 (pbk): 978-1-4842-1918-8 ISBN-13 (electronic): 978-1-4842-1919-5DOI 10.1007/978-1-4842-1919-5
Library of Congress Control Number: 2016941346
Copyright © 2016 by Changyi Gu
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While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Managing Director: Welmoed SpahrLead Editor: Jonathan GennickDevelopment Editor: Douglas PundickTechnical Reviewer: Brendan HoranEditorial Board: Steve Anglin, Pramila Balen, Louise Corrigan, Jim DeWolf, Jonathan Gennick,
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Printed on acid-free paper
To those who enjoy doing things that are otherwise meaningless in the eyes of many.
Contents at a Glance
About the Author .....................................................................................................xv
About the Technical Reviewer ...............................................................................xvii
Acknowledgments ..................................................................................................xix
Introduction ............................................................................................................xxi
■Chapter 1: The Whole Picture ................................................................................ 1
■Chapter 2: Power On and Bootloader .................................................................... 5
■Chapter 3: Inside the CPU .................................................................................... 27
■Chapter 4: RAM, DMA, and Interrupt ................................................................... 47
■Chapter 5: Bus Architecture ................................................................................ 69
■Chapter 6: Firmware Coding in C ....................................................................... 103
■Chapter 7: Firmware Coding in the C++ and Script Languages ........................ 129
■Chapter 8: Building and Deployment ................................................................. 149
■Chapter 9: Field-Programmable Gate Arrays ..................................................... 191
■Chapter 10: System on Programmable Chip (SOPC) .......................................... 233
■Chapter 11: De-Bounce, Power Management, and Display ................................ 249
■Chapter 12: Fixed Point Math ............................................................................ 271
■Chapter 13: Popular Ways of Console Communications: Prepare the Tools ...... 305
■Chapter 14: Work Flow ...................................................................................... 313
Index ..................................................................................................................... 317
v
Contents
About the Author .....................................................................................................xv
About the Technical Reviewer ...............................................................................xvii
Acknowledgments ..................................................................................................xix
Introduction ............................................................................................................xxi
■Chapter 1: The Whole Picture ................................................................................ 1
Organization of the Book .................................................................................................. 3
Companion Materials for this Book .................................................................................. 4
References ....................................................................................................................... 4
■Chapter 2: Power On and Bootloader .................................................................... 5
What Happens After Powering On .................................................................................... 5
What Does Bootloader Do? ............................................................................................... 7
User Image (ROM Image).................................................................................................. 8
Image of Embedded OS .......................................................................................................................... 8
Image of Object File ................................................................................................................................ 9
Flash Image and XIP (Execute In Place) ................................................................................................ 14
Flash Memory ................................................................................................................. 20
Burn the Flash (PROM Program) ........................................................................................................... 20
NOR Flash and NAND Flash .................................................................................................................. 20
Pre-Loader ............................................................................................................................................ 22
Flash File System ................................................................................................................................. 23
Summary ........................................................................................................................ 24
References ..................................................................................................................... 25
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■ CONTENTS
viii
■Chapter 3: Inside the CPU .................................................................................... 27
Von Neumann Architecture and Memory Barrier ............................................................ 27
Harvard Architecture, Modifi ed Harvard Architecture ..................................................... 29
CISC and RISC ................................................................................................................ 31
SIMD/VLIW ...................................................................................................................... 34
CPU Debugging ............................................................................................................... 34
CPU Simulator ....................................................................................................................................... 34
ROM Monitor ......................................................................................................................................... 35
Introduction to ICE (In Circuit Emulator) ............................................................................................... 35
Non-JTAG ICE ........................................................................................................................................ 36
JTAG-Based ICE .................................................................................................................................... 38
Using Breakpoints ................................................................................................................................ 42
Trace ..................................................................................................................................................... 44
Summary ........................................................................................................................ 46
References ..................................................................................................................... 46
■Chapter 4: RAM, DMA, and Interrupt ................................................................... 47
Types of Random Access Memory .................................................................................. 47
NVRAM (Non-Volatile Random Access Memory) ................................................................................... 47
Traditional SRAM: Intel 8080 vs. Motorola 6800 ................................................................................... 47
DDR SDRAM (Dual Date Rate Synchronous Dynamic RAM) .................................................................. 50
QDR SRAM ............................................................................................................................................ 53
Other Types of RAM .............................................................................................................................. 54
PIO and DMA .................................................................................................................. 55
PIO ........................................................................................................................................................ 55
DMA and MMU ...................................................................................................................................... 56
Memory Allocation for DMA .................................................................................................................. 59
Cache/Write Buffer and Memory Incoherence ...................................................................................... 60
Interrupt ......................................................................................................................... 61
Interrupt Mechanism ............................................................................................................................ 61
Shared Interrupt ................................................................................................................................... 62
■ CONTENTS
ix
VIC (Vectored Interrupt Controller) ........................................................................................................ 66
Interrupt from Watchdog Timer ............................................................................................................. 67
Message Signaled Interrupt (MSI) ........................................................................................................ 67
Summary ........................................................................................................................ 68
References ..................................................................................................................... 68
■Chapter 5: Bus Architecture ................................................................................ 69
Bus with System Synchronous Timing ........................................................................... 69
Bus with Source Synchronous Timing ............................................................................ 70
From Parallel Bus to Serial Bus ...................................................................................... 72
The Drawbacks of Parallel Bus ............................................................................................................. 73
The Benefi t of Differential Serial Link ................................................................................................... 75
Implementation of Differential Serial Link ...................................................................... 77
Out-of-band Clocking ........................................................................................................................... 77
Embedded Clocking .............................................................................................................................. 79
8b/10b Encoding and Signal Conditioning ............................................................................................ 80
Bus Standards ................................................................................................................ 80
RS-232 .................................................................................................................................................. 80
I2C and SMBus ..................................................................................................................................... 81
SPI ........................................................................................................................................................ 82
PCI overview ......................................................................................................................................... 82
USB overview ....................................................................................................................................... 85
USB device implementation.................................................................................................................. 87
Ethernet ................................................................................................................................................ 92
Summary ...................................................................................................................... 101
References ................................................................................................................... 101
■Chapter 6: Firmware Coding in C ....................................................................... 103
Overview ...................................................................................................................... 103
The Confusion of Tongues ............................................................................................ 105
■ CONTENTS
x
Firmware Coding in the C Language ............................................................................ 106
Explicit Type of Bit-Width .................................................................................................................... 106
Align the Data Structure ..................................................................................................................... 107
Debug Print ......................................................................................................................................... 109
Compile Time Assertion ...................................................................................................................... 112
Volatile, Const, and Peripheral Registers ............................................................................................ 112
Finite State Machine ........................................................................................................................... 121
Firmware Version and About Signature .............................................................................................. 125
Summary ...................................................................................................................... 127
References ................................................................................................................... 127
■Chapter 7: Firmware Coding in the C++ and Script Languages ........................ 129
Firmware Coding in C++ .............................................................................................. 129
Enhancements to the C Language ...................................................................................................... 130
New Concepts Offered by C++ ........................................................................................................... 136
C/C++ Mixed Programming ......................................................................................... 142
Script Languages Overview.......................................................................................... 143
Compiled Versus Script Languages .................................................................................................... 143
Tcl/Tk, Expect, Perl, and Python ......................................................................................................... 144
Documentation Generator ................................................................................................................... 145
Summary ...................................................................................................................... 146
References ................................................................................................................... 147
■Chapter 8: Building and Deployment ................................................................. 149
The Build Process ......................................................................................................... 149
Makefi le Basics .................................................................................................................................. 149
Simple Makefi le .................................................................................................................................. 152
Makefi les that Handle Dependency .................................................................................................... 154
Recursive Makefi les ........................................................................................................................... 156
Makefi le with Kernel Confi guration Language.................................................................................... 163
Other Ways to Implement a Build Process .......................................................................................... 174
■ CONTENTS
xi
Embedded OS ............................................................................................................... 181
Choose an Embedded OS ................................................................................................................... 181
Embedded Linux Development Flow .................................................................................................. 183
Development Machine Setup .............................................................................................................. 183
Summary ...................................................................................................................... 188
References ................................................................................................................... 188
■Chapter 9: Field-Programmable Gate Arrays ..................................................... 191
Hardware Overview ...................................................................................................... 191
FPGA ............................................................................................................................. 192
CPU vs. FPGA ...................................................................................................................................... 192
Verilog vs. VHDL .................................................................................................................................. 194
Bi-Directional Bus ............................................................................................................................... 206
Clock ................................................................................................................................................... 208
Reset................................................................................................................................................... 210
CDC (Clock Domain Crossing) ............................................................................................................. 213
Area-Time Tradeoff and AT2 Boundary ................................................................................................ 219
Inter-FPGA Communication ................................................................................................................. 225
Protect Your IP .............................................................................................................. 226
Encrypt Your Source Code .................................................................................................................. 227
Obfuscate Your Source Code .............................................................................................................. 227
Protect Your Bit Stream ...................................................................................................................... 227
Anti-Tamper ........................................................................................................................................ 228
Summary ...................................................................................................................... 230
References ................................................................................................................... 230
■Chapter 10: System on Programmable Chip (SOPC) .......................................... 233
Economics 101 ............................................................................................................. 233
MCU vs. Soft MCU ............................................................................................................................... 234
MCU Plus External Peripherals ........................................................................................................... 234
Multiple Processors ............................................................................................................................ 235
■ CONTENTS
xii
Processor Core ............................................................................................................. 236
Interconnection ............................................................................................................ 238
Design and Use Your Own 1T 8051 .............................................................................. 238
History 101 ......................................................................................................................................... 238
Patents and Copyrights....................................................................................................................... 239
Address Spaces .................................................................................................................................. 240
CISC Instruction Set ............................................................................................................................ 242
RISC Implementation .......................................................................................................................... 244
Compilers and Debuggers .................................................................................................................. 246
Summary ...................................................................................................................... 247
References ................................................................................................................... 247
■Chapter 11: De-Bounce, Power Management, and Display ................................ 249
PoR (Power-On Reset) and Switch De-Bounce ............................................................. 249
Power-On Reset .................................................................................................................................. 249
Switch De-Bounce .............................................................................................................................. 251
Power Management ..................................................................................................... 253
LCD Display .................................................................................................................. 253
How LCD Works .................................................................................................................................. 254
LCD Programming Interfaces .............................................................................................................. 258
Using Touchscreens...................................................................................................... 263
Resistive Touchscreens ...................................................................................................................... 263
Capacitive Touchscreen ...................................................................................................................... 265
Summary ...................................................................................................................... 268
References ................................................................................................................... 268
■Chapter 12: Fixed Point Math ............................................................................ 271
Q Format ....................................................................................................................... 271
Two’s Complement and Symmetric Range .................................................................. 272
Basic Operations .......................................................................................................... 272
Rounding and Truncation .................................................................................................................... 272
Saturation ........................................................................................................................................... 273
■ CONTENTS
xiii
Negation ............................................................................................................................................. 275
Absolute Value .................................................................................................................................... 276
Unsigned Division ............................................................................................................................... 276
Sin/Cos Table ...................................................................................................................................... 284
CORDIC Algorithm ......................................................................................................... 286
Basic Ideas ......................................................................................................................................... 286
Circular Coordinate System ................................................................................................................ 288
Linear Coordinate System .................................................................................................................. 293
Hyperbolic Coordinate System ........................................................................................................... 297
Summary ...................................................................................................................... 302
References ................................................................................................................... 303
■Chapter 13: Popular Ways of Console Communications: Prepare the Tools ...... 305
Software Tools .............................................................................................................. 305
Cygwin ................................................................................................................................................ 305
Text Editor ........................................................................................................................................... 305
File/Folder Comparison....................................................................................................................... 306
Version Control ................................................................................................................................... 306
Issue (Bug) Tracking ........................................................................................................................... 307
Terminal Emulator .............................................................................................................................. 308
Virtual Machine ................................................................................................................................... 309
Cluster Workload Management .......................................................................................................... 309
Hardware Tools ............................................................................................................. 309
Oscilloscope ....................................................................................................................................... 309
Logic Analyzer .................................................................................................................................... 310
Bus/Protocol Analyzer-Exerciser ......................................................................................................... 310
Power Analyzer ................................................................................................................................... 310
Multimeter .......................................................................................................................................... 311
Others ................................................................................................................................................. 311
Summary ...................................................................................................................... 311
References ................................................................................................................... 312
■ CONTENTS
xiv
■Chapter 14: Work Flow ...................................................................................... 313
Project Inception .......................................................................................................... 314
System Design ............................................................................................................. 314
Software ............................................................................................................................................. 314
Hardware ............................................................................................................................................ 315
Mechanical ......................................................................................................................................... 315
Manufacturing and Quality Control ............................................................................... 315
Summary ...................................................................................................................... 316
References ................................................................................................................... 316
Index ..................................................................................................................... 317
About the Author
Changyi Gu has worked for multiple high-tech companies across California for over 15 years. He is also the founder of PulseRain Technology, LLC, a company that excels at FPGA-based embedded systems. He started out his career in firmware development. With a deep passion in engineering, he later devoted himself to wireless hardware and programmable logic. Thus, he is one of the lucky few who gets to watch things closely on both the software and hardware sides.
Changyi graduated from the University of Southern California with a master’s degree in VLSI. And he holds another master’s degree in Communications and a bachelor’s degree in CS from Shanghai Jiaotong University, China. In his leisure time, he likes to tinker with things.
xv
About the Technical Reviewer
Brendan Horan is a hardware fanatic, with a full high rack of all types of machine architectures in his home. He has more than 10 years of experience working with large UNIX systems and tuning the underlying hardware for optimal performance and stability. Brendan’s love for all forms of hardware has helped him throughout his IT career, from fixing laptops to tuning servers and their hardware in order to suit the needs of high-availability designs and ultra low-latency applications. Brendan takes pride in the Open Source Movement and is happy to say that every computer in his house is powered by open source technology. He resides in Hong Kong with his wife, Vikki, who continues daily to teach him more Cantonese.
xvii
Acknowledgments
Family:
First of all, I would like to thank my parents for nurturing my interest in engineering since childhood, which has given rise to this book.
I would also like to thank my wife and daughter for bearing with my nocturnal lifestyle for so long. The midnight oil I burned is in your names.
Tech Reviewers:
Special thanks to Brendan Horan for his sound suggestions to my writing. Those feedbacks are highly valued.
And I also owe a big thank you to my ex-coworkers—Cynthia Xu and On Wa Yeung—for offering assistance in reading my book. I really appreciate your kind help.
Editors:
A hug to Jonathan Gennick for giving me the opportunity on this book, and for his passion in embedded systems. I really appreciate your prompt response to my book proposal and your hard work throughout the whole project.
I would also like to thank Jill Balzano for her wonderful job managing the project. This book will not be possible without you.
My development editor, Douglas Pundick, offered valuable suggestions to save me from possible embarrassment. Your thoroughness is appreciated.
And to the rest of Apress team—thanks for your hard work!
Readers:
Thank you for choosing my book!
xix
Introduction
“Almost no one comes down here (the engineering level) unless, of course, there is a problem. That’s how it is with people. Nobody cares how it works as long as it works. I like it down here.”
—The Matrix Reloaded (2003)
Embedded systems are conspicuous by their omnipresence. But most people take them for granted despite the fact that behind every system is a design that involves multiple engineering disciplines. Even something as humble as a toaster might be the joint effort of software and hardware engineers. Assuming you still have the unabated curiosity to know how stuff works, this book will try to fill any knowledge gaps you might run into.
Actually, this book is a brain dump of what I have picked up over the past 15+ years. Some of this knowledge has been learned the hard way, which is passively through insomnia and hair loss. And it is my best wishes that you don’t have to go through the same ordeals I endured.
In addition to the traditional design approach, the semiconductor industry’s latest juggernaut has made SOPC (System on Programmable Chips) a viable option both technologically and financially. It is a trail blazed by many newly designed embedded systems, which this book explores in depth.
Lastly, this book will serve you better if you’ve taken some college-level courses in CS or EE, or maybe a little bit of both. Basic knowledge in C/C++ and FPGA can help you sail through this book more smoothly.
Thank you for your faith in my book!
—Changyi Gu 02/14/2016 in San Diego, CA
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