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Embedded Signal Processing with the Micro Signal

1. Axis Selection Oy Cancel Settings Figure 1 16 Plot Configuration dialog box 6 Build the project by following the steps given in Hands On Experiment 1 1 Run the project and verify that the correct result in array c is displayed in the Output Window HANDS ON EXPERIMENT 1 3 1 In this hands on experiment we introduce some useful graphic features in the VisualDSP environment We plot the three arrays a b and c used in the previ ous experiment 2 Make sure that the project is built and loaded into the simulator Click on View gt Debug Windows Plot gt New A Plot Configuration dialog box appears as shown in Figure 1 16 We type in a and 20 and select int in Address Count and 18 Chapter 1 Introduction Array a 5 000 Values 0 2 4 6 8 10 12 14 16 18 20 22 Number of elements Figure 1 17 Display of array a Data boxes respectively Click on Add to add in the array a Use similar steps to plot the other two arrays Modify the plot settings to make a graph as displayed in Figure 1 17 3 Finally add in the other two arrays in the same plot or create two new plots So far we have learned how to program in C and run the code with the Blackfin simulator and EZ KITs In the following section we introduce a new graphical development environment LabVIEW Embedded Module for Blackfin Processors
2. 1 3 3 Advanced Setup Using the Blackfin BF533 or BF537 EZ KIT In the previous hands on experiments we ran the program with the BF533 or BF537 simulator In this section we perform the same experiment with the Blackfin 1 3 Introduction to the Integrated Development Environment VisualDSP 13 I J R Audio loupat General purpose we LEDs C lt babes General ppagpose iy d push buttons a Lad i b a SW4eSW35 SWG SW Figure 1 10 The BF533 EZ KIT BF533 or BF537 EZ KIT The EZ KIT board is a low cost hardware platform that includes a Blackfin processor surrounded by other devices such as audio coder decoder CODEC video encoders video decoders flash synchronous dynamic RAM SDRAM and so on We briefly introduce the hardware components in the EZ KIT and show the differences between the BF533 and BF537 boards Figure 1 10 shows a picture of the BF533 EZ KIT 29 This board has four audio input and six audio output channels via the RCA jacks In addition it can also encode and decode three video inputs and three video outputs Users can also program the four general purpose push buttons SW4 SW5 SW6 and SW7 and six general purpose LEDs LED4 LED9 The EZ KIT board is inter faced with the VisualDSP hosted on personal computer via the USB interface cable Figure 1 11 shows a picture of the BF537 EZ KIT 30 This board consists of stereo input and output jack connectors H
3. 8 4 2 Power Management in the Blackfin Processor 360 8 5 Sample Rate Conversion with Blackfin Simulator 365 8 6 Sample Rate Conversion with BF533 BF537 EZ KIT 369 8 7 Sample Rate Conversion with LabVIEW Embedded Module for Blackfin Processors 371 8 8 More Exercise Problems 374 Part C Real World Applications 9 Practical DSP Applications Audio Coding and Audio Effects 381 9 1 Overview of Audio Compression 381 9 2 MP3 Ogg Vorbis Audio Encoding 386 9 3 MP3 Ogg Vorbis Audio Decoding 390 x Contents 9 4 Implementation of Ogg Vorbis Decoder with BF537 EZ KIT 391 9 5 Audio Effects 393 9 5 1 3D Audio Effects 393 9 5 2 Implementation of 3D Audio Effects with BF533 BF537 EZ KIT 396 9 5 3 Generating Reverberation Effects 398 9 5 4 Implementation of Reverberation with BF533 BF537 EZ KIT 399 9 6 Implementation of MDCT with LabVIEW Embedded Module for Blackfin Processors 400 9 7 More Application Projects 404 10 Practical DSP Applications Digital Image Processing 406 10 1 Overview of Image Representation 406 10 2 Image Processing with BF533 BF537 EZ KIT 409 10 3 Color Conversion 410 10 4 Color Conversion with BF533 BF537 EZ KIT 412 10 5 Two Dimensional Discrete Cosine Transform 413 10 6 Two Dimensional DCT IDCT with BF533 BF537 EZ KIT 416 10 7 Two Dimensional Filtering 417 10 7 1 2D Filtering 418 10 7 2 2D Filter Design 420 10 8 Two Dimensional Filtering with BF533 BF537 EZ KIT 422 10 9 Image Enhancement 422 10 9 1 Gaussian White No
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5. The result is saved in the third array c Use File New File to create a blank page for editing in the VisualDSP Save these files in directory c adsp chapl exp1_2 2 From the File menu choose New and then Project to open the Project Wizard Enter the directory and the name of the new project as shown in Figure 1 13 Click on Finish and Yes to create a new project 3 An empty project is created in the Project window Click on Project gt Project Options to display the Project Options dialog box as shown in Figure 1 14 The default settings are used and the project creates an executable file dxe Because Settings for configuration is set to Debug the executable file also contains debug information for debugging 4 Click on Compile gt General 1 and click on Enable optimization to enable the optimization for speed as shown in Figure 1 15 Click OK to apply changes to the project options 5 To add the source files to the new project click on Project Add to Project gt File s Select the two source files and click Add The sources files are now added to the project file 16 Chapter 1 Introduction Project Wizard Project Information Choose the name location and type of project that you would like to create Diy General Day Output Type Add Startup Code 3885 Finish Directory c adsp chap exp1_2 Project types its Standard application Library Multithreaded application
6. jointly developed by NI and ADI This new tool provides an efficient approach to prototyping embedded signal processing systems This new rapid prototyping tool uses a graphical user interface GUI to control and select parameters of the signal processing algorithms and view updates of graphical plots on the fly 1 5 SYSTEM LEVEL DESIGN USING A GRAPHICAL DEVELOPMENT ENVIRONMENT Graphical development environments such as National Instruments LabVIEW are effective means to rapidly prototype and deploy developments from indivi dual algorithms to full system level designs onto embedded processors The graphi cal data flow paradigm that is used to create LabVIEW programs or virtual instruments VIs allows for rapid intuitive development of embedded code This is due to its flowchart like syntax and inherent ease in implementing parallel tasks In this section and sections included at the end of each subsequent chapter we present a common design cycle that engineers are using to reduce product develop ment time by effectively integrating the software tools they use on the desktop for deployment and testing This will primarily be done with the LabVIEW Embedded 1 5 System Level Design Using a Graphical Development Environment 19 Development Module for the ADI Blackfin BF533 and BF537 processors which is an add on module for LabVIEW to target and deploy to the Blackfin processor Other LabVIEW add ons such as the Digital Filter Design Toolkit
7. ANALOG DEVICES MEMORY Ogg Vorbis STREA DECODED AUDI AUDIO AUDIO COMPRESSED COMPRESSED AUDI B A O OVER SERIAL POF DAC OUTPU AUDIO DATA LACK ue y SDRAM Figure 1 2 A block diagram of the audio media player courtesy of Analog Devices Inc system the compressed audio bit stream in Ogg Vorbis format introduced in Chapter 9 is stored in the flash memory external to the embedded processor a Blackfin processor A decoding program for decoding the audio bit stream is loaded from the boot flash memory into the processor s memory The compressed data are streamed into the Blackfin processor which decodes the compressed bit stream into pulse code modulated PCM data The PCM data can in turn be enhanced by some postprocessing tasks like equalization reverberation and three dimensional audio effects presented in Chapter 9 The external audio digital to analog converter DAC converts the PCM data into analog signal for playback with the headphones or loudspeakers Using this audio media player as an example we can identify several common characteristics in typical embedded systems They are summarized as follows 1 Dedicated functions An embedded system usually executes a specific task repeatedly In this example the embedded processor performs the task of decoding the Ogg Vorbis bit stream and sends the decoded audio samples to the DAC for playback 2 Tight constraints Th
8. Ethernet on the BF537 and through JTAG USB on both the BF537 and BF533 pro cessors To use instrumented debug run the application in debug mode using the Debug button Ey Try changing vector elements on the front panel and probing wires on the block diagram For additional configuration setup and debugging information refer to Getting Started with the LabVIEW Embedded Module for Analog Devices Blackfin Processors 52 found in the book companion website i 1 6 More Exercise Problems 21 6 MORE EXERCISE PROBLEMS List 10 embedded systems in Table 1 1 that are required to perform some forms of DSP Explain the signal processing tasks Survey the key components in a typical iPod player Survey the key components in a typical digital camera Survey the differences between fixed function processors and programmable processors State the advantages and disadvantages of these processors In Hands on Experiment 1 1 C language is used to program the Blackfin processor A low level assembly program can also be used to compute the dot product The low level assembly code uses a standard set of assembly syntaxes These assembly syntaxes are introduced in Chapter 5 onward Use the Blackfin simulator either BF533 or BF537 to create a new project file that includes the source codes available in directory c adsp chap1 problem1_5 Examine the source files and understand the differences between the C function code in Experiment
9. Figure 1 12 setup for the BF533 EZ KIT Click OK and note the change in the title bar of the VisualDSP We are now ready to run the same project on the BF533 EZ KIT Similarly if the BF537 EZ KIT is used select the desired processor and its EZ KIT Build the project and run the executable file on the EZ KIT using the same procedure as before Do you notice any difference in the building process on the EZ KIT platform compared to the simulator Next obtain the cycle count in running the same program on the EZ KIT Is there any change in the cycle count as com pared to the simulator 1 4 More Hands on Experiments 15 gt New Session Debug target Processor Blackfin Emulators EZ KIT Lites v ADSP BF533 Platform ADSP BF533 EZ KIT Lite viaDebugAgent RY Session name ADSP BF533 ADSP BF533 EZ KIT Lite via Debu C Show all targets and platforms OK Cancel Licenses Configurator Figure 1 12 New Session window setup for BF533 EZ KIT 1 4 MORE HANDS ON EXPERIMENTS We have learned how to load a project file into the Blackfin simulator and EZ KIT In this section we create a new project file from scratch and use the graphic features in the VisualDSP environment The following experiments apply to both BF533 and BF537 EZ KITs HANDS ON EXPERIMENT 1 2 1 Using the previous source files as templates create two new source files vecadd_main c and vecadd c to perform vector addition of two arrays a and b
10. and Design of Active Noise Control Systems with the TMS320 Family Texas Instruments 1996 His research focuses on real time digital signal processing applications active noise and vibration control adaptive echo and noise cancellation digital audio applications and digital communications Note A number of illustrations appearing in this book are reproduced from copy right material published by Analog Devices Inc with permission of the copyright owner A number of illustrations and text appearing in this book are reprinted with the permission of National Instruments Corp from copyright material VisualDSP is the registered trademark of Analog Devices Inc LabVIEW and National Instruments are trademarks and trade names of National Instruments Corporation MATLAB is the registered trademark of The MathWorks Inc Thanks to the Hackles for providing audioclips from their singles Leave It Up to Me copyright 2006 www TheHackles com xix Chapter l Introduction 1 1 EMBEDDED PROCESSOR MICRO SIGNAL ARCHITECTURE Embedded systems are usually part of larger and complex systems and are usually implemented on dedicated hardware with associated software to form a computa tional engine that will efficiently perform a specific function The dedicated hard ware or embedded processor with the associated software is embedded into many applications Unlike general purpose computers which are designed to perfo
11. may also be discussed Embedded system developers frequently use computer simulation and design tools such as LabVIEW and the Digital Filter Design Toolkit to quickly develop a system or algorithm for the needs of their project Next the developer can leverage his her simulated work on the desktop by rapidly deploying that same design with the LabVIEW Embedded Module for Blackfin Processors and continue to iterate on that design until the design meets the design specifications Once the design has been completed many developers will then recode the design using VisualDSP for the most efficient implementation Therefore knowledge of the processor archi tecture and its C assembly programming is still important for a successful imple mentation This book provides balanced coverage of both high level programming using the graphical development environment and conventional C assembly pro gramming using VisualDSP In the first example using this graphical design cycle we demonstrate the implementation and deployment of the dot product algorithm presented in Hands On Experiment 1 1 using LabVIEW and the LabVIEW Embedded Module for Blackfin Processors 1 5 1 Setting up LabVIEW and LabVIEW Embedded Module for Blackfin Processors LabVIEW and the LabVIEW Embedded Module for Blackfin Processors trial version can be downloaded from the book companion website A brief tutorial on using these software tools is included in Appendix A of this book On
12. noises such as thermal noise generated by thermal agitation of electrons in electrical devices To enhance the signals we must use different techniques based on the characteristics of signals and noise to reduce the undesired noise components In many practical applications a complete statistical characterization of a random variable may not be available The useful measures associated with a random signal are mean variance and autocorrelation functions For stationary signals the mean or expected value is independent of time and is defined as 2 2 Time Domain Digital Signals 29 my E x n 1 iS OFA tet aN DIY 20 2 2 7 where the expectation operator E extracts an average value The variance is defined as 63 E x n m E x n m 2 2 8 Note that the expected value of the square of a random variable is equivalent to the average power The MATLAB function mean x gives the average of the data in vector x The function y var x returns the variance of the values in the vector x and the function std x computes the standard derivation o The mean of a uniformly distributed random variable in the interval X X2 is given as ee a 2 2 9 2 The variance is 2 genn 2 2 10 12 The MATLAB function rand generates arrays of random numbers whose elements are uniformly distributed in the interval 0 1 The function rand with no argu ments is a scalar whose value changes each time it is referenced In addition
13. of processor allows users to write software for the specific applications The software programming approach has the flexibility of writing different algorithms for different products using the same processor and upgrading the code to meet emerging standards in existing products Therefore a product can be pushed to the market in a shorter time frame and this significantly reduces the development cost compared to the hard wired approach A programmable digital signal processor is commonly used in many embedded applications DSP architecture has evolved greatly over the last two decades to include many advanced features like higher clock speed multiple multi pliers and arithmetic units incorporation of coprocessors for control and commu nication tasks and advanced memory configuration The complexity of today s signal processing applications and the need to upgrade often make a programmable embedded processor a very attractive option In fact we are witnessing a market shift toward software based microarchitectures for many embedded media process ing applications One of the latest classes of programmable embedded signal processors is the micro signal architecture MSA The MSA core 43 was jointly developed by Intel and Analog Devices Inc ADI to meet the computational demands and power con straints of today s embedded audio video and communication applications The MSA incorporates both DSP and microcontroller functionalities in a si
14. rate and I O bandwidth Software issues include program ming language software techniques and programming the processor s resources A good tool can greatly speed up the process of developing and debugging the software and ensure that real time processing can be achieved Chapter 7 explains the peripherals and I O transfer mechanism of the Black fin processor whereas Chapter 8 describes the techniques used in optimizing the code in C and assembly programming 5 Integration of software and hardware in embedded system A final part of this book implements several algorithms for audio and image applications The Blackfin BF533 BF537 EZ KITs are used as the platform for integration of software and hardware To start the design of the embedded system we can go through a series of exercises using the development tools As we progress to subsequent chapters more design and debugging tools and features of these tools are introduced This progres sive style in learning the tools will not overload the users at the beginning We use only the right tool with just enough features to solve a given problem 1 3 INTRODUCTION TO THE INTEGRATED DEVELOPMENT ENVIRONMENT VISUALDSP In this section we examine the software development tool for embedded signal processors The software tool for the Blackfin processor is the VisualDSP 33 supplied by ADI VisualDSP is an integrated development and debugging environment IDDE that provides complete grap
15. 1 1 and the assembly function code listed in this exercise Benchmark and compare the cycle count for performing the same dot product with assembly code with that obtained with C code Also benchmark the C code with optimization enabled Implement the same project in the Blackfin either BF533 or BF537 EZ KIT Any dif ference in the cycle counts compared to the Blackfin simulator Table 1 1 DSP Tasks in Embedded Systems Embedded Systems DSP Tasks 2 3 4 5 6 7 8 9 10 22 Chapter 1 Introduction 7 The Fibonacci series can be computed by adding the two successive numbers to form the next number in the series Generate the Fibonacci series for the first 10 numbers of 1 1 2 3 5 8 13 21 34 55 using the Blackfin simulator starting from the first two numbers Verify your answer in the Blackfin memory window 8 Refer to the ADI manual on getting started with VisualDSP 34 and go through all the experiments described in the manual The manual can be found in the ADI website Part A Digital Signal Processing Concepts Chapter 2 Time Domain Signals and Systems This chapter uses several noise reduction examples and experiments to introduce important time domain techniques for processing digital signals and analyzing simple DSP systems The detailed analysis and more advanced methods are intro duced in Chapter 3 using frequency domain techniques 2 1 INTRODUCTION Wit
16. 17 6 1 1 Fixed Point Formats 217 6 1 2 Fixed Point Extended Format 229 6 1 3 Fixed Point Data Types 231 6 1 4 Emulation of Floating Point Format 231 6 1 5 Block Floating Point Format 235 viii Contents 6 2 Dynamic Range Precision and Quantization Errors 236 6 2 1 Incoming Analog Signal and Quantization 236 6 2 2 Dynamic Range Signal to Quantization Noise Ratio and Precision 238 6 2 3 Sources of Quantization Errors in Digital Systems 240 6 3 Overview of Real Time Processing 250 6 3 1 Real Time Versus Offline Processing 250 6 3 2 Sample by Sample Processing Mode and Its Real Time Constraints 251 6 3 3 Block Processing Mode and Its Real Time Constraints 252 6 3 4 Performance Parameters for Real Time Implementation 255 6 4 Introduction to the IIR Filter Based Graphic Equalizer 260 6 5 Design of IIR Filter Based Graphic Equalizer Using Blackfin Simulator 261 6 6 Design of IIR Filter Based Graphic Equalizer with BF533 BF537 EZ KIT 266 6 7 Implementation of IIR Filter Based Graphic Equalizer with LabVIEW Embedded Module for Blackfin Processors 266 6 8 More Exercise Problems 270 7 Memory System and Data Transfer 274 71 Overview of Signal Acquisition and Transfer to Memory 274 7 1 1 Understanding the CODEC 274 7 1 2 Connecting AD1836A to BF533 Processor 276 7 1 3 Understanding the Serial Port 282 7 2 DMA Operations and Programming 287 7 2 1 DMA Transfer Configuration 289 7 2 2 Setting Up the Autobuffer Mode DMA 291 7 2 3 Memory DMA Tra
17. DSP concepts B embedded processor architecture and real time DSP considerations and C real life applications a simple A B C xiv Preface Part A Digital Signal Processing Concepts Chapter 2 Time Domain Signals and Systems Chapter 3 Frequency Domain Analysis and Processing Chapter 4 Digital Filtering Part B Embedded Signal Processing Systems and Concepts Chapter 5 Introduction to the Blackfin Processor Chapter 6 Real Time DSP Fundamentals and Implementation Considerations Chapter 7 Memory System and Data Transfer Chapter 8 Code Optimization and Power Management Part C Real World Applications Chapter 9 Audio Coding and Audio Effects Chapter 10 Digital Image Processing This part may be skipped for those who already familiar with DSP However it serves as a quick reference It provides a good platform for learning software tools Part B integrates the embedded processor s architecture programming and integrating hardware and software into a complete embedded system It provides a good platform to learn the in depth details of development tools It contains many hands on examples and exercises in using the Blackfin processors Explore more advanced real time and real world applications Implement a working prototype running on the Blackfin EZ KIT Lite Figure 1 Summary of the book contents and how to use them approach to learning embedded signal processing with the micro sig
18. Embedded Signal Processing with the Micro Signal Architecture Woon Seng Gan Sen M Kuo IEEE IEEE PRESS BICENTENNIAL 11807 WILEY J 2007 BICENTENNIAL WILEY INTERSCIENCE A John Wiley amp Sons Inc Publication Embedded Signal Processing with the Micro Signal Architecture BICENTENNIAL f TVINNALINIDI9 BICENTENNIAL THE WILEY BICENTENNIAL KNOWLEDGE FOR GENERATIONS ach generation has its unique needs and aspirations When Charles Wiley first opened his small printing shop in lower Manhattan in 1807 it was a generation of boundless potential searching for an identity And we were there helping to define a new American literary tradition Over half a century later in the midst of the Second Industrial Revolution it was a generation focused on building the future Once again we were there supplying the critical scientific technical and engineering knowledge that helped frame the world Throughout the 20th Century and into the new millennium nations began to reach out beyond their own borders and a new international community was born Wiley was there expanding its operations around the world to enable a global exchange of ideas opinions and know how For 200 years Wiley has been an integral part of each generation s journey enabling the flow of information and understanding necessary to meet their needs and fulfill their aspirations Today bold new technologies are changing the way we liv
19. MATLAB provides the function randn for generating normally distributed random numbers with zero mean and unit variance QUIZ 2 2 1 Compute the mean and variance of random numbers generated by the MATLAB function rand 2 How do we generate the zero mean m 0 and unit variance 0 1 random numbers that are uniformly distributed with rand EXAMPLE 2 2 Similar to Example 2 1 we generate 60 samples of a sine wave that is corrupted by noise using the MATLAB script example2_2 m The generated noisy samples are saved in data file sineNoise dat and the original sine wave and the corrupted sine wave are shown in Figure 2 2
20. On Experiments 47 2 6 Implementation of Moving Average Filters with Blackfin Simulator 50 prs Implementation of Moving Average Filters with BF533 BF537 EZ KIT 52 2 8 Moving Average Filter in LabVIEW Embedded Module for Blackfin Processors 54 29 More Exercise Problems 51 3 Frequency Domain Analysis and Processing 59 3 1 Introduction 59 3 2 The z Transform 60 3 2 1 Definitions 60 3 2 2 System Concepts 62 3 2 3 Digital Filters 64 33 Frequency Analysis 70 3 3 1 Frequency Response 70 3 3 2 Discrete Fourier Transform 76 3 3 3 Fast Fourier Transform 78 3 3 4 Window Functions 83 3 4 More Hands On Experiments 88 3 4 1 Simple Low Pass Filters 88 3 4 2 Design and Applications of Notch Filters 91 3 4 3 Design and Applications of Peak Filters 96 3 3 Frequency Analysis with Blackfin Simulator 98 3 6 Frequency Analysis with Blackfin BF533 BF537 EZ KIT 102 3 Frequency Analysis with LabVIEW Embedded Module for Blackfin Processors 105 3 8 More Exercise Problems 110 4 Digital Filtering 112 4 1 Introduction 112 4 1 1 Ideal Filters 113 4 1 2 Practical Filter Specifications 115 4 2 Finite Impulse Response Filters 120 4 2 1 Characteristics and Implementation of FIR Filters 121 4 2 2 Design of FIR Filters 123 4 2 3 Hands On Experiments 126 4 3 Infinite Impulse Response Filters 129 4 3 1 Design of IIR Filters 129 4 3 2 Structures and Characteristics of IIR Filters 133 4 3 3 Hands On Experiments 136 Contents vii 44 Adaptive Filters 139 4 4 1 Struct
21. ackfin processors include BF534 BF536 and BF537 These processors operate at around 400 500 MHz and feature a strong support for Ethernet connection and a wider range of peripherals 6 Chapter 1 Introduction Because all Blackfin processors are code compatible the programs written for one processor can be easily ported to other processors This book uses BF533 and BF537 processors to explain architecture programming peripheral interface and implementation issues The main differences between the BF533 and the BF537 are the additional peripheral supports and slightly less internal instruction memory of the BF537 processors Therefore explanation of the Blackfin processing core can be focused solely on the BF533 and additional sections are introduced for the extra peripheral supports in the BF537 There are several low cost development tools introduced by ADI In this book we use the VisualDSP simulator to verify the correctness of the algorithm and the EZ KIT development board that contains the MSA processor memory and other peripherals for the Blackfin BF533 and BF537 processors for real time signal processing and control applications In addition we also use a new tool LabVIEW Embedded Module for Blackfin Processors jointly developed by National Instru ments NI and ADI to examine a new approach in programming the Blackfin pro cessor with a blockset programming approach 1 2 REAL TIME EMBEDDED SIGNAL PROCESSING DSP plays an i
22. ce they are installed double click on National Instruments LabVIEW 7 1 Embedded Edition under the All Programs panel of the start menu Hands On Experiment 1 4 provides an introduction to the LabVIEW Embedded Module for Blackfin Processors to explore concepts from the previous hands on experiments HANDS ON EXPERIMENT 1 4 This exercise introduces the NI LabVIEW Embedded Module for Blackfin Processors and the process for deploying graphical code on the Blackfin processor for rapid prototyping and verification The dot product application was created with the same vector values used pre viously in the VisualDSP project file exp1_1 dpj This experiment uses arrays func tions and the Inline C Node within LabVIEW From the LabVIEW Embedded Project Manager window open the project file DotProd BF5xx lep located in directory c adsp chapl exp1_4 Next double click on Dot Prod_BF vi from within the project window to open the front panel The front panel is the graphical user interface GUI which contains the inputs and outputs of the 20 Chapter 1 Introduction 4 Vector Dot Product Result p e Jo Hee Hi0 Has jo Vector B i p Y do Afas Hius A 7 Figure 1 18 Front panel of DotProd vi J _ Pot Product Result mazz Dot Product vi aa Inline C Node i j azz A printF The Dot Product is f n value Figure 1 19 Block diagram of DotProd vi pf23 program as shown in Figure 1 18 Select View Block Diagram to s
23. dents who have taken our DSP courses and have written M S theses and Ph D dissertations and completed senior design projects under our guidance at both NTU and NIU Both institutions have provided us with a stimulating environment for research and teach ing and we appreciate the strong encouragement and support we have received Finally we are greatly indebted to our parents and families for their understanding patience and encouragement throughout this period WOON SENG GAN AND SEN M Kuo xvii About the Authors Woon Seng Gan is an Associate Professor in the Information Engineering Division in the School of Electrical and Electronic Engineering at the Nanyang Technological University in Singapore He is the co author of the textbook Digital Signal Proces sors Architectures Implementations and Applications Prentice Hall 2005 He has published more than 130 technical papers in peer reviewed journals and international conferences His research interests are embedded media processing embedded systems low power consumption algorithms and real time implementations Sen M Kuo is a Professor and Chair at the Department of Electrical Engineering Northern Illinois University DeKalb IL In 1993 he was with Texas Instruments Houston TX He is the leading author of four books Active Noise Control Systems Wiley 1996 Real Time Digital Signal Processing Wiley 2001 2nd Ed 2006 Digital Signal Processors Prentice Hall 2005
24. e Micro Signal Architecture by Woon Seng Gan and Sen M Kuo p cm Includes bibliographical references and index ISBN 978 0 471 73841 1 1 Signal processing Digital techniques 2 Embedded computer systems Programming 3 Computer architecture I Kuo Sen M Sen Maw II Title TK5102 9 G364 2007 621 382 2 dc22 2006049693 Printed in the United States of America 100987654321 Contents Preface xi Acknowledgments xvii About the Authors xix 1 Introduction 1 1 1 Embedded Processor Micro Signal Architecture 1 2 Real Time Embedded Signal Processing 6 LS Introduction to the Integrated Development Environment VisualDSP 7 1 3 1 Setting Up VisualDSP 8 1 3 2 Using a Simple Program to Illustrate the Basic Tools 9 1 3 3 Advanced Setup Using the Blackfin BF533 or BF537 EZ KIT 12 14 More Hands On Experiments 15 1 5 System Level Design Using a Graphical Development Environment 18 1 5 1 Setting up LabVIEW and LabVIEW Embedded Module for Blackfin Processors 19 1 6 More Exercise Problems 21 Part A Digital Signal Processing Concepts 2 Time Domain Signals and Systems 25 2 1 Introduction 25 2 2 Time Domain Digital Signals 26 2 2 1 Sinusoidal Signals 26 2 2 2 Random Signals 28 2 3 Introduction to Digital Systems 33 2 3 1 Moving Average Filters Structures and Equations 34 2 3 2 Digital Filters 37 2 3 3 Realization of FIR Filters 41 vi Contents 2 4 Nonlinear Filters 45 2 5 More Hands
25. e and learn Wiley will be there providing you the must have knowledge you need to imagine new worlds new possibilities and new opportunities Generations come and go but you can always count on Wiley to provide you the knowledge you need when and where you need it Voi lO BS Etl WILLIAM J PESCE PETER BOOTH WILEY PRESIDENT AND CHIEF EXECUTIVE OFFICER CHAIRMAN OF THE BOARD Embedded Signal Processing with the Micro Signal Architecture Woon Seng Gan Sen M Kuo IEEE IEEE PRESS BICENTENNIAL 11807 WILEY J 2007 BICENTENNIAL WILEY INTERSCIENCE A John Wiley amp Sons Inc Publication Copyright 2007 by John Wiley amp Sons Inc All rights reserved Published by John Wiley amp Sons Inc Hoboken New Jersey Published simultaneously in Canada No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording scanning or otherwise except as permitted under Section 107 or 108 of the 1976 United States Copyright Act without either the prior written permission of the Publisher or authorization through payment of the appropriate per copy fee to the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 978 750 8400 fax 978 750 4470 or on the web at www copyright com Requests to the Publisher for permission should be addressed to the Permissions Department John Wiley amp Sons
26. ectors a and b From the Settings menu choose Preferences to open the dialog box as shown in Figure 1 6 10 Chapter 1 Introduction Project exp1_1 dpj Jx A Project Group 1 project o py exp1_1 include lt stdio h gt 5 cn r include lt stdlib h gt SY Source Files include lt math h gt dotprod c E dotprod_main c LJ Linker Files global variables LI Header Files int af jl Project Figure 1 5 Snapshot of the C file dotprod_main c displayed in the source window Preferences T Cors Eh Commands E Editor General Preferences jez V Reset targets before load Load executable after build E Keyboard E Plugins V Run to main after load Auto complete commands E Project C Prompt on target halt Dock new windows E Toolbars Eh Tools Enable pipeline display Check external file modification C Recycle source windows Fonts Element IDDE Window Font Output Window Font Courier Figure 1 6 Preferences dialog box Under the General preference click on Run to main after load and Load executable after build The first option starts executing from the void main of the program after the program is loaded into the simulator The second option enables the code to be loaded into the processor memory after the code is being built The rest of the options can be left as default Click OK to close the Preferences dialog box Now we are ready to build the project We can either c
27. edded processors the software tools and the Blackfin xvi Preface processor will also undergo many changes as time evolves The versions of software tools used in this book are e MATLAB Version 7 0 e VisualDSP Version 4 0 e LabVIEW 8 0 e LabVIEW Embedded Edition 7 1 This website keeps track of the latest changes and new features of these tools It also reports on any compatibility problems when running existing experiments with the newer version of software All the programs mentioned in the exercises and experiments are available for download in the Wiley ftp site ftp ftp wiley com public sci_tech_med embedded_signal We also include a feedback section to hear your comments and suggestions Alternatively readers are encouraged to email us at ewsgan ntu edu sg and kuo ceet niu edu Learning Objective We learn by example and by direct experience because there are real limits to the adequacy of verbal instruction Malcolm Gladwell Blink The Power of Thinking Without Thinking 2005 Acknowledgments W are very grateful to many individuals for their assistance in developing this book In particular we are indebted to Todd Borkowski of Analog Devices who got us started in this book project Without his constant support and encourage ment we would not have come this far We would like to thank Erik B Luther Jim Cahow Mark R Kaschner and Matt Pollock of National Instruments for contri buting to the expe
28. ere are many constraints in designing an embedded system such as cost processing speed size and power consumption In this example the digital media player must be low cost so that it is affordable to most consumers it must be small enough to fit into the pocket and the battery life must last for a long time 3 Reactive and real time performance Many embedded systems must con tinuously react to changes of the system s input For example in the digital media player the compressed data bit stream can be decoded in a number of cycles per audio frame or operating frequency for real time processing In addition the media player also must respond to the change of mode selected by the users during playback 4 Chapter 1 Introduction Therefore the selection of a suitable embedded processor plays an important role in the embedded system design A commonly used approach for realizing signal processing tasks is to use fixed function and hardwired processors These are imple mented as application specific integrated circuits ASICs with DSP capabilities However these hardwired processors are very expensive to design and produce as the development costs become significant for new process lithography In addition proliferation and rapid change of new standards for telecommunication audio image and video coding applications makes the hardwired approach no longer the best option An alternative is to use programmable processors This type
29. erstanding it is difficult to program and optimize code using embedded signal processors for real world applications However the use of C code as a main program that calls intrinsic and DSP library functions is still the preferred programming style for the Blackfin processor It is important to think in low level architecture but write in high level code C or graphical data flow Therefore we show how to balance high level and low level programming and introduce the techniques needed for optimization In addition we also introduce a very versatile xi xii Preface graphical tool jointly developed by ADI and National Instruments NJ that allows users to design simulate implement and verify an embedded system with a high level graphical data flow approach The progressive arrangement makes this book suitable for engineers They may skip some topics they are already familiar with and focus on the sections they are interested in The following subsections introduce the essential parts of this book and how these parts are linked together PART A USING SOFTWARE TOOLS TO LEARN DSP A JUST IN TIME AND PROJECT ORIENTED APPROACH In Chapters 2 3 and 4 we explore fundamental DSP concepts using a set of software tools from the MathWorks ADI and NI Rather than introducing all theo retical concepts at the beginning and doing exercises at the end of each chapter we provide just enough information on the required concepts for solving the g
30. external devices These supporting hardware units and the processing core are the typical building blocks that form an embedded system The embedded processor is connected to the real world analog devices as shown in Figure 1 1 In addition the embedded processor can exchange data with another system or processor by digital I O channels In this book we use hands on experiments to illustrate how to program various blocks of the embedded system and how to integrate them with the core embedded processor In most embedded systems the embedded processor and its interfaces must operate under real time constraints so that incoming signals are required to be processed within a certain time interval Failure to meet these real time constraints results in unacceptable outcomes like noisy response in audio and image applica tions or even catastrophic consequences in some human related applications like automobiles airplanes and health monitoring systems In this book the terms embedded processing and real time processing are often used interchangeably to include both concepts In general an embedded system gathers data processes them and makes a decision or responds in real time To further illustrate how different blocks are linked to the core embedded pro cessor we use the example of a portable audio player shown in Figure 1 2 In this 1 1 Embedded Processor Micro Signal Architecture 3 BOOT FLASH MEMORY FIRMWARE FLASH
31. gap from DSP concepts to real time implemen tations on embedded processors and providing a starting point for students to embark on real time signal processing programming with a fixed point embedded processor PART C DESIGNING AND IMPLEMENTING REAL TIME DSP ALGORITHMS AND APPLICATIONS AN INTEGRATED APPROACH The final part Chapters 9 and 10 motivates users to take on more challenging real time applications in audio signal processing and image processing Students can use the knowledge and tools learned in the preceding chapters to complete the applications introduced in Chapters 9 and 10 Some guides in the form of basic concepts block diagrams sample code and suggestions are provided to solve these application problems We use a module approach in Part C to build the embedded system part by part and also provide many opportunities for users to explore new algorithms and applications that are not covered in Parts A and B These application examples also serve as good mini projects for a hands on design course on embed ded signal processing As in many engineering problems there are many possible solutions There are also many opportunities to make mistakes and learn valuable lessons Users can explore the references and find a possible solution for solving these projects In other words we want the users to explore learn and have fun A summary of these three parts of the book is illustrated in Figure 1 It shows three components A
32. gs Tools Window Help Osha S s 2 ala f ORS Project Window m oy Project Group 0 project FFA00000 FFA00002 FFA00004 FFA00006 FFA00008 FFAQOO0A FFAQOO0C FFAQO00E FFA00010 FF 00012 FFA00014 FFA00016 FFA00018 FFA0001A x Qutput Window I Console Build J Figure 1 4 VisualDSP window this and following chapters Click on Project Project Options and make sure that the right processor is selected for the targeted simulator 1 3 2 Using a Simple Program to Illustrate the Basic Tools In this section we illustrate the basic tools and features in the VisualDSP IDDE through a series of simple exercises We use a sample project that consists of two source files written in C for the Blackfin processor HANDS ON EXPERIMENT 1 1 In this experiment we first start the VisualDSP environment as explained above Next click on the File menu in the toolbar menu and select Open Project Look for the project file exp1_1 dpj under directory c adsp chapl exp1_1 and double click on the project file Once the project file is loaded into the VisualDSP environment we can see a list of source files Double click on dotprod_main c to see the source code in the editor window right side as shown in Figure 1 5 Scroll through the source code in both dotprod_main c and dotprod c This is a simple program to perform multiply accumulate or dot product of two v
33. h the easy accessibility of increasingly powerful personal computers and the availability of powerful and easy to use MATLAB 48 software for computer simulations we can now learn DSP concepts more effectively This chapter uses hands on methods to introduce fundamental time domain DSP concepts because it is more interesting to examine real world DSP applications with the help of interactive MATLAB tools In particular this chapter uses the latest powerful graphical user interface GUI tool called Signal Processing Tool which comes with the Signal Processing Toolbox 49 Because each experiment requires a set of general problem solving skills and related DSP principles we provide multiple contexts including the necessary DSP theory computer simulations and hands on experiments for achieving thorough understanding Most of the DSP subjects are covered in the introduction to hands on exercises and experiments These experiments are organized to introduce DSP subjects from the simple introductory subjects in this chapter and gradually introduce more complicated experiments and applications in subsequent chapters Each experiment introduces and applies just enough information at that time to complete the required tasks This is similar to using a spiral learning technique to continually circle back and cover concepts in more and more depth throughout Chapters 2 3 and 4 Embedded Signal Processing with the Micro Signal Architecture By Woo
34. hical control of the edit build and debug processes In this section we show the detailed steps of loading a project file into the IDDE building it and downloading the executable file into the simulator or the EZ KIT We introduce some important features of the VisualDSP in this chapter and more advanced features are introduced in sub sequent chapters 8 Chapter 1 Introduction 1 3 1 Setting Up VisualDSP The Blackfin version of VisualDSP IDDE can be downloaded and tested for a period of 90 days from the ADI website Once it is downloaded and installed a VisualDSP Environment icon irt will appear on the desktop Double click on this icon to activate the VisualDSP A New Session window will appear as shown in Figure 1 3 Select the Debug target Platform and Processor as shown in Figure 1 3 and click OK to start the VisualDSP Under the Debug target option there are two types of Blackfin simulator a cycle accurate interpreted simulator and a functional compiled simulator When ADSP_BF5xx Blackfin Family Simulators is selected the cycle accurate simulator is used This simulator provides a more accurate performance and thus is usually used in this book The compiled simulator is used when the simulator needs to process a large data file The Processor option allows users to select the type of processor In this book only the Blackfin BF533 and BF537 processors are covered However the code developed for any Blackfin pr
35. ht time This book introduces just in time and just enough information on embedded signal processing using the embedded processors based on the micro signal archi tecture MSA In particular we examine the MSA based processors called Blackfin processors from Analog Devices ADI We extract relevant and sufficient informa tion from many resources such as textbooks electronic books the ADI website signal processing related websites and many journals and magazine articles related to these topics The just in time organization of these selective topics provides a unique experience in learning digital signal processing DSP For example students no longer need to learn advanced digital filter design theory before embarking on the actual design and implementation of filters for real world applications In this book students learn just enough essential theory and start to use the latest tools to design simulate and implement the algorithms for a given application If they need a more advanced algorithm to solve a more sophisticated problem they are now more confident and ready to explore new techniques This exploratory attitude is what we hope students will achieve through this book We use assembly programming to introduce the architecture of the embedded processor This is because assembly code can give a more precise description of the processor s architecture and provide a better appreciation and control of the hard ware Without this und
36. ial ports mixed signal circuits external memory interfaces and other peripherals and devices to form an embedded system Chapter 7 illustrates how to program and configure some of these peripherals to work with the core pro cessor Chapter 8 explains and demonstrates several important techniques of opti mizing the program written for the MSA core This chapter also illustrates a unique feature of the MSA core to control the clock frequency and supply voltage to the MSA core via software so as to reduce the power consumption of the core during active operation In this book we examine the MSA core with the latest Blackfin processors BF5xx series from ADI The first generation of Blackfin processors is the BF535 processor which operates at 300 MHz and comes with L1 and L2 cache memories system control blocks basic peripheral blocks and high speed I O The next genera tion of Blackfin processors consists of BF531 BF532 BF533 and BF561 processors These processors operate at a higher clock speed of up to 750MHz and contain additional blocks like parallel peripheral interface voltage regulator external memory interface and more data and instruction cache The BF531 and BF532 are the least expensive and operate at 400 MHz and the BF561 is a dual core Blackfin processor that is targeted for very high end applications The BF533 processor oper ates at 750 MHz and provides a good platform for media processing applications Recently released Bl
37. igning a hard real time system Some of the challenges include 1 Understanding DSP concepts and algorithms A solid understanding of the important DSP principles and algorithms is the key to building a suc cessful real time system With this knowledge designers can program and optimize the algorithm on the processor using the best parameters and set 1 3 Introduction to the Integrated Development Environment VisualDSP 7 tings Chapters 2 to 4 introduce the fundamentals of DSP and provide many hands on experiments to implement signal processing algorithms 2 Resource availability The selection of processor core peripherals sensors and actuators user interface memory development and debugging tools is a complex task There are many critical considerations that make the deci sion tough Chapter 5 shows the architecture of the Blackfin processor and highlights its strength in developing the embedded system 3 Arithmetic precision In most embedded systems a fixed point arithmetic is commonly used because fixed point processors are cheaper consume less power and have higher processing speed as compared to floating point pro cessors However fixed point processors are more difficult to program and also introduce many design challenges that are discussed in Chapter 6 4 Response time requirements Designers must consider hardware and soft ware issues Hardware considerations include processor speed memory size and its transfer
38. ise and Linear Filtering 423 10 9 2 Impulse Noise and Median Filtering 425 10 9 3 Contrast Adjustment 428 10 10 Image Enhancement with BF533 BF537 EZ KIT 432 10 11 Image Processing with LabVIEW Embedded Module for Blackfin Processors 433 10 12 More Application Projects 438 Appendix A An Introduction to Graphical Programming with LabVIEW 441 Appendix B Useful Websites 462 Appendix C List of Files Used in Hands On Experiments and Exercises 464 Appendix D Updates of Experiments Using Visual DSP V4 5 473 References 475 Index 479 Preface I this digital Internet age information can be received processed stored and transmitted in a fast reliable and efficient manner This advancement is made pos sible by the latest fast low cost and power efficient embedded signal processors Embedded signal processing is widely used in most digital devices and systems and has grown into a must have category in embedded applications There are many important topics related to embedded signal processing and control and it is impos sible to cover all of these subjects in a one or two semester course However the Internet is now becoming an effective platform in searching for new information and this ubiquitous tool is enriching and speeding up the learning process in engineering education Unfortunately students have to cope with the problem of information overflow and be wise in extracting the right amount of material at the rig
39. iven problems and supplement with many quizzes interactive examples and hands on exercises along the way in a just in time manner Students learn the concepts by doing the assignments for better understanding This approach is especially suitable for studying these subjects at different paces and times thus making self learning possible In addition to these hands on exercises the end of each chapter also provides challenging pen and paper and computer problems for homework assignments These problem sets build upon the previous knowledge learned and extend the thinking to more advanced concepts These exercises will motivate students in looking for different solutions for a given problem The goal is to cultivate a learning habit after going through the book The theory portion of these chapters may be skipped for those who have taken a fundamental course on DSP Nonetheless these examples and hands on exercises serve as a handy reference on learning important tools available in MATLAB the integrated development environment VisualDSP and the LabVIEW Embedded Module for Blackfin Processors These tools provide a platform to convert theoreti cal concepts into software code before learning the Blackfin processor in detail The introduction to the latest LabVIEW Embedded Module for Blackfin Processors shows the advancement in rapid prototyping and testing of embedded system designs for real world applications This new tool provides exciting oppor
40. lick on Project gt Build Project in the toolbar menu or press the function key F7 There is a build icon that 1 3 Introduction to the Integrated Development Environment VisualDSP 11 can be used to perform the build operation The build operation basically combines the compile assembler and link processes to obtain an executable file dxe Users will find the executable file exp1_1 dxe being created in directory c adsp chapl exp1_1 debug after the build operation Besides the Build Project option there is the Rebuild All option or icon The Rebuild All option builds the project regardless of whether the project build is up to date The message Build completed successfully is shown in the Build page of the Output Window if the build process detects no error However users will notice that the build process detects an undefined identifier as shown in Figure 1 7 Users can double click on the error message in red and the cursor will be placed on the line that contains the error Correct the typo by changing results to result and save the source file by clicking on File Save File dotprod_main c The project is now built without any error as indicated in the Output window Once the project has been built the executable file exp1_1 dxe is automatically downloaded into the target enabled in the Preferences dialog box which is the BF533 or BF537 simulator Click on the Console page of the Output Window A message appea
41. m 0Hz to f 2 Hz which results in a distortion called aliasing The sampling theorem implies that digital signals can only have meaningful representation of signal components from 0 Hz to f 2 Hz EXAMPLE 2 1 We can generate a 200 Hz sine wave that is sampled at 4 000Hz or 4kHz using the MATLAB program example2_1 m A partial code is listed as follows fs 4000 sampling rate is 4 kHz 200 frequency of sinewave is 200 Hz n O7lsfs Ff time index n that cover one cycle xn sin 2 pi f n fs generate sinewave plot n xn o grid on The generated sine wave is shown in Figure 2 1 in which the digital samples are marked by open circles Digital signal x n consists of those discrete time samples however we usually 200 Hz sine wave sampled at 4 000 Hz 1 T 5 T T T T T T Amplitude A I 0 2 4 6 8 10 12 14 16 18 20 Time index nTs Figure 2 1 One cycle of 200 Hz sine wave sampled at 4 000Hz Signal samples are marked by open circles 28 Chapter 2 Time Domain Signals and Systems plot a digital signal by connecting those samples with a line such as x t shown in Figure 2 1 Based on Equation 2 2 1 the sampling period T 1 4 000s As shown in Figure 2 1 one cycle of sine wave consists of 20 samples Therefore the period of sine wave is 1 4 000 x 20 1 200s which is equivalent to the frequency of 200 Hz QUIZ 2 1 1 If the sine wave shown in Figure 2 1 is obtained by sampling an a
42. mportant role in many real time embedded systems A real time embedded system is a system that requires response to external inputs within a specific period For example a speech recognition device sampling speech at 8 kHz bandwidth of 4kHz must respond to the sampled signal within a period of 125 us Therefore it is very important that we take special attention to define the real time system and highlight some special design considerations that apply to real time embedded signal processing systems Generally a real time system must maintain a timely response to both internal and external signal data There are two types of real time system hard and soft real time systems For the hard real time system an absolute deadline for the com pletion of the overall task is imposed If the hard deadline is not met the task has failed For example in the case of speech enhancement the DSP software must be completed within 125 Us otherwise the device will fail to function correctly In the case of a soft real time system the task can be completed in a more relaxed time range For example it is not critical how long it takes to complete a credit card transaction There is no hard deadline by which the transaction must be completed as long as it is within a reasonable period of time In this book we only examine hard real time systems because all embedded media processing systems are hard real time systems There are many important challenges when des
43. n Seng Gan and Sen M Kuo Copyright 2007 John Wiley amp Sons Inc 25 26 Chapter 2 Time Domain Signals and Systems Projects introduced in this chapter are based on designing simple filters to remove broadband white noise that corrupts the desired narrowband sinusoidal signal First a MATLAB example shows how to generate a digital signal and use it to introduce a sampling theorem A quiz is provided immediately afterward to ensure that we understand the relationship between analog and digital worlds A hands on experiment implements the moving average filter with length L 5 10 and 20 using the MATLAB code We find that when the filter is working for L 5 it reduces more noise when L 10 with higher undesired signal attenuation but are surprised to learn that the filter output approaches zero when L 20 Finally for more complicated problems of adding different noises sinusoidal and white to the speech we have to enhance the desired speech We use the simple moving average filter but fail Now our interest is piqued to learn more advanced DSP techniques in Chapters 3 and 4 In this fashion we learn important DSP concepts repeatedly at each project by doing hands on experiments and exercises We con tinually circle back the DSP subjects and cover concepts in more and more depth throughout the book 2 2 TIME DOMAIN DIGITAL SIGNALS A digital signal x n is defined as a function of time index n which corresponds to time a
44. nal architecture DESCRIPTION OF EXAMPLES EXERCISES EXPERIMENTS PROBLEMS AND APPLICATION PROJECTS This book provides readers many opportunities to understand and explore the main contents of each chapter through examples quizzes exercises hands on experi ments exercise problems and application projects It also serves as a good hands on workbook to learn different embedded software tools MATLAB VisualDSP and LabVIEW Embedded and solve practical problems These hands on sections are classified under different types as follows 1 Examples provide a just in time understanding of the concepts learned in the preceding sections Examples contain working MATLAB problems to illustrate the concepts and how problems can be solved The naming conven tion for software example files is Preface XV example chapter number example number m They are normally found in the directory c adsp chap x MATLAB_ex x where x is the chapter number 2 Quizzes contain many short questions to challenge the readers for immedi ate feedback of understanding 3 Experiments are mostly hands on exercises to get familiar with the tools and solve more in depth problems These experiments usually use MATLAB VisualDSP or LabVIEW Embedded The naming convention for software experiment files is exp chapter number example number These experiment files can be found in the directory c adsp chap x exp x _ no _ lt option gt where n
45. nalog sine wave with a sampling rate of 100 Hz what is the frequency of the sine wave Why 2 If the frequency of the sine wave shown in Figure 2 1 is 20Hz what is the sampling period used for obtaining these digital samples Why 3 If we want to produce 3s of analog sine wave by converting a digital sine wave with a digital to analog D A converter DAC with a sampling rate of 4kHz how many digital samples are needed Quiz 2 1 shows that the frequency of a digital signal is dependent on the sam pling rate f Therefore it is more convenient to use the normalized digital frequency defined as FSf G 2 1 lt F lt 1 2 2 6 with unit cycles per sample Comparing this definition with Equation 2 2 4 we show that Fr For example the digital frequency of the sine wave shown in Figure 2 1 is F 0 1 or 0 17 In many real world applications the operation of sampling analog signals is implemented by an analog to digital A D converter ADC Similarly the opera tion of converting digital signals to analog forms is realized by a D A converter These devices are introduced in Section 2 7 for real time experiments 2 2 2 Random Signals The sine wave shown in Figure 2 1 is a deterministic signal because it can be defined exactly by a mathematical equation Eq 2 2 3 In practice the signals encountered in the real world such as speech music and noise are random signals In addition the desired signals are often corrupted by
46. ngle core Both Intel and ADI have further developed processors based on the MSA architecture for different applications The MSA core combines a highly efficient computational architecture with features usually only available on microcontrollers These features include optimizations for high level language programming memory protection and byte addressing Therefore the MSA has the ability to execute highly complex DSP algorithms and basic control tasks in a single core This combination avoids the need for a separate DSP processor and microcontroller and thus greatly simplifies both hardware and software design and implementation In addition the MSA has a very efficient and dynamic power management feature that is ideal for a variety of battery powered communication and consumer applications that require high intensity signal processing on a strict power budget In fact the MSA based processor is a versatile platform for processing video image audio voice and data Inside the computational block of the MSA there are two multiply add units two arithmetic logic units and a single shifter These hardware engines allow the MSA based processor to efficiently perform several multiply add operations in 1 1 Embedded Processor Micro Signal Architecture 5 parallel to support complex number crunching tasks The availability of these hard ware units coupled with high clock speed starts from 300 MHz and rises steadily to the 1 GHz range has crea
47. nsfer 297 7 2 4 Setting Up Memory DMA 298 7 2 5 Examples of Using Memory DMA 298 7 2 6 Advanced Features of DMA 302 T3 Using Cache in the Blackfin Processor 303 7 3 1 Cache Memory Concepts 303 7 3 2 Terminology in Cache Memory 305 7 3 3 Instruction Cache 307 7 3 4 Data Cache 310 7 3 5 Memory Management Unit 313 7 4 Comparing and Choosing Between Cache and Memory DMA 315 7 5 Scratchpad Memory of Blackfin Processor 317 Contents ix 7 6 Signal Generator Using Blackfin Simulator 317 77 Signal Generator Using BF533 BF537 EZ KIT 319 7 8 Signal Generation with LabVIEW Embedded Module for Blackfin Processors 321 7 9 More Exercise Problems 326 8 Code Optimization and Power Management 330 8 1 Code Optimization 330 8 2 C Optimization Techniques 331 8 2 1 C Compiler in VisualDSP 332 8 2 2 C Programming Considerations 333 8 2 3 Using Intrinsics 339 8 2 4 Inlining 342 8 2 5 C C Run Time Library 343 8 2 6 DSP Run Time Library 343 8 2 7 Profile Guided Optimization 346 8 3 Using Assembly Code for Efficient Programming 349 8 3 1 Using Hardware Loops 352 8 3 2 Using Dual MACs 353 8 3 3 Using Parallel Instructions 353 8 3 4 Special Addressing Modes Separate Data Sections 355 8 3 5 Using Software Pipelining 356 8 3 6 Summary of Execution Cycle Count and Code Size for FIR Filter Implementation 357 8 4 Power Consumption and Management in the Blackfin Processor 358 8 4 1 Computing System Power in the Blackfin Processor 358
48. o indicates the experiment number and lt option gt indicates the BF533 or BF537 EZ KIT 4 Exercises further enhance the student s learning of the topics in the preced ing sections examples and experiments They also provide the opportunity to attempt more advanced problems to strengthen understanding 5 Exercise Problems are located at the end of Chapters 1 to 8 These problem sets explore or extend more interesting and challenging problems and experiments 6 Application Projects are provided at the end of Chapters 9 and 10 to serve as mini projects Students can work together as a team to solve these application oriented projects and submit a report that indicates their approaches algorithms and simulations and how they verify the projects with the Blackfin processor Most of the exercises and experiments require testing data We provide two directories that contain audio and image data files These files are located in the directories c adsp audio_files and c adsp image_files COMPANION WEBSITE A website www ntu edu sg home ewsgan esp_book html has been set up to support the book This website contains many supplementary materials and useful reference links for each chapter We also include a set of lecture slides with all the figures and tables in PowerPoint format This website will also introduce new hands on exercises and new design problems related to embedded signal processing Because the fast changing world of emb
49. oces sor is compatible with other Blackfin processors In Figure 1 3 the ADSP BF533 simulator is selected Alternatively users can select the ADSP BF537 simulator A VisualDSP Version 4 window is shown in Figure 1 4 There are three subwindows and one toolbar menu in the VisualDSP window A Project Window displays the files available in the project or project group The Disassembly window displays the assembly code of the program after the project has been built The Output Window consists of two pages Console and Build The Console page displays any message that is being programmed in the code and the Build page shows any errors encountered during the build process The toolbar menu contains all the tools options and modes available in the VisualDSP environment We will illustrate these tools as we go through the hands on examples and exercises in gt New Session Debug target Processor ADSP BF5xx Blackfin Family Simulators ADSP BF531 3 ADSP BF532 Platform ADSP BF533 ADSP BF534 ADSP BF5xx Single Processor Simulator ADSP BF536 ADSP BF537 Session name ADSP BF538 ADSP BF533 ADSP BF5xx Single Processor Simul moar es C Show all targets and platforms Figure 1 3 A New Session window 1 3 Introduction to the Integrated Development Environment VisualDSP 9 gt Analog Devices VisualDSP Target ADSP BF533 ADSP BF5xx Single Processor Simulator eR File Edit Session View Project Register Memory Debug Settin
50. owever the BF537 EZ KIT does not have any video I O Instead it includes the IEEE 802 3 10 100 Ethernet media access control and controller area network CAN 2 0B controller Similar to the BF533 EZ KIT the BF537 EZ KIT has four general purpose push buttons SW10 SW11 SW12 and SW13 and six general purpose LEDs LEDI LED6 Other feature differences between BF533 and BF537 EZ KITs are highlighted in subsequent chapters 14 Chapter 1 Introduction Figure 1 11 The BF537 EZ KIT This section describes the setup of the BF533 EZ KIT 31 The EZ KIT s power connector is first connected to the power supply Turn on the power supply and verify that the green LED is lit and LEDs 4 9 continue to roll indicating that the board is not linked to the software Next the USB cable is connected from the computer to the EZ KIT board The window environment recognizes the new hard ware and launches the Add New Hardware Wizard which installs files located on the EZ KIT CD ROM Once the USB driver is installed successfully the yellow LED USB monitor should remain lit A similar setup can also be carried out for the BF537 EZ KIT 32 Users can refer to the BF533 or BF537 EZ KIT Evalua tion System Manual for more details on the settings The VisualDSP environment can be switched to the EZ KIT target by the following steps Click on Session gt New Session A New Session window will appear Change the debug target and platform to that shown in
51. r 1 Introduction Breakpoints Breakpoint Properties Break at oK main Ox4 Browse Cancel Expression Add Skip Breakpoint list at___lib_prog_term v Dame Figure 1 9 Breakpoint dialog box Disassembly window The breakpoint can be set or cleared by double clicking on the gray gutter Fig 1 8 next to the target code in the editor and disassembly window The project is now ready to run Click on the run button or Debug Run F5 The simulator computes the dot product sum of products or multiply accumulate and dis plays the result in the Console page of the Output Window What is the answer for the dot product between arrays a and b Modify the source files to perform the following tasks 1 Add a new 20 element array c perform the dot product computation between arrays a and c and display the result 2 Recompute the dot product of the first 10 elements in the arrays 3 To obtain the cycle count of running the code from start to finish we can use the cycle registers Simply click on Register gt Core Cycles Reload the program by clicking on File Reload Program The program pointer will reset to the begin ning of the program In the Cycle window clear the CYCLE register value to 0 to initialize the cycle counter Run the program and note the cycle count Note To display the cycle count in unsigned integer format right click on the Cycle window and select unsigned integer
52. r battery and interfacing chips for I O data transfer and communicates or exchanges information with other embedded processors A typical embedded system with some necessary supporting hardware is shown in Figure 1 1 A single or multiple embedded processing core is used to Embedded Signal Processing with the Micro Signal Architecture By Woon Seng Gan and Sen M Kuo Copyright 2007 John Wiley amp Sons Inc 2 Chapter 1 Introduction External Memory Analog to Digital Converter Embedded Processing Core Digital to t Analog Converter System Peripherals Input Output Embedded Processor Device Figure 1 1 Block diagram of a typical embedded system and its peripherals perform control and signal processing functions Hardware interfaces to the process ing core include 1 internal memories such as read only memory ROM for boot loading code and random access memory RAM and cache for storing code and data 2 a direct memory access DMA controller that is commonly used to transfer data in and out of the internal memory without the intervention of the main process ing core 3 system peripherals that contain timers clocks and power management circuits for controlling the processor s operating conditions and 4 I O ports that allow the embedded core to monitor or control some external events and process incoming media streams from
53. riments examples and writing in the LabVIEW Embedded Module for Blackfin Processors Without their strong commitment and support we would never have been able to complete many exciting demos within such a short time The first author would like to thank Chandran Nair and Siew Hoon Lim of National Instruments for providing their technical support and advice We would also like to thank David Katz and Dan Ledger of Analog Devices for providing useful advice on Blackfin processors Additionally many thanks to Mike Eng Dick Sweeney Tonny Jiang Li Chuan Mimi Pichey and Dianwei Sun of Analog Devices Several individuals at John Wiley also provided great help to make this book a reality We wish to thank George J Telecki Associate Publisher for his support of this book Special thanks must go to Rachel Witmer Editorial Program Coordi nator who promptly answered our questions We would also like to thank Danielle Lacourciere and Dean Gonzalez at Wiley for the final preparation of this book The authors would also like to thank Dahyanto Harliono who contributed to the majority of the Blackfin hands on exercises in the entire book Thanks also go to Furi Karnapi Wei Chee Ku Ee Leng Tan Cyril Tan and Tany Wijaya who also contributed to some of the hands on exercises and examples in the book We would also like to thank Say Cheng Ong for his help in testing the LabVIEW experiments This book is also dedicated to many of our past and present stu
54. rm many general tasks an embedded system is a specialized computer system that is usually integrated as part of a larger system For example a digital still camera takes in an image and the embedded processor inside the camera compresses the image and stores it in the compact flash In some medical instrument applications the embedded processor is programmed to record and process medical data such as pulse rate and blood pressure and uses this information to control a patient support system In MP3 players the embedded processor is used to process compressed audio data and decodes them for audio playback Embedded processors are also used in many consumer appliances including cell phones personal digital assistants PDA portable gaming devices digital versatile disc DVD players digital cam corders fax machines scanners and many more Among these embedded signal processing based devices and applications digital signal processing DSP is becoming a key component for handling signals such as speech audio image and video in real time Therefore many of the latest hardware processing units are equipped with embedded processors for real time signal processing The embedded processor must interface with some external hardware such as memory display and input output I O devices such as coder decoders to handle real life signals including speech music image and video from the analog world It also has connections to a power supply o
55. rs stating that the executable file has been completely loaded into the target and there is a Breakpoint Hit at lt ffa006f8 gt A solid red circle indicates breakpoint and a yellow arrow indicates the current location of the program pointer are positioned at the left hand edges of the source code and disassembly code as shown in Figure 1 8 The VisualDSP automatically sets two breakpoints one at the beginning and the other at the end of the code The location of the breakpoint can be viewed by clicking on Setting Breakpoints as shown in Figure 1 9 Users can click on the breakpoint under the Breakpoint list and click the View button to find the location of the breakpoint in the x dotprod_main c dotprod_main c line 81 ccO020 error identifier results is undefined results a_dot_bf a b E error detected in the compilation of dotprod_main c fatal error Compilation failed Tool failed with exit exception code 1 Build was unsuccessful Console A Build Figure 1 7 Error message appears after building the project ra rral Disassembly void main Editor window FFA window main int result 0 F LINK Oxo result a dot b a b rat Fi ME a _ vintf Dot product d n result S r 5 P Red circle and yellow arrow 3 FF CALL a_dot_b Figure 1 8 Breakpoint displayed in both editor and disassembly windows 12 Chapte
56. t nT seconds if the signal is sampled from an analog signal x f with the sampling period 7 seconds The sampling period can be expressed as 1 To 2 2 1 fs where f is the sampling frequency or sampling rate in hertz or cycles per second For many real world applications the required sampling rates are defined by the given applications For example the sampling rate for telecommunications is 8 000 Hz or 8kHz and for compact discs CDs it is 44 1 kHz 2 2 1 Sinusoidal Signals An analog sine wave can be expressed as x t Asin 27ft Asin Qt 2 2 2 where A is the amplitude f is the frequency of the sine wave in hertz and Q 2nf is the frequency in radians per second If we sample this analog sine wave with sampling rate f we obtain a digital sine wave x n with samples at time 0 T 2T nT This digital signal can be expressed by replacing t with nT in Equation 2 2 2 as x n x nT Asin 2nfnT Asin n 2 2 3 where the digital frequency in radians per sample or simply radians is defined as 2 2 Time Domain Digital Signals 27 w 2nfT 2nf f TSON 2 2 4 It is important to note that the sampling rate must satisfy the Nyquist sampling theorem expressed as f22In 2 2 5 where fy is the maximum frequency component or bandwidth of the signal which is also called a Nyquist frequency If f lt 2fy frequency components higher than f 2 will fold back to the frequency range fro
57. ted a substantial speed improvement over conventional microprocessors The detailed architecture of the MSA core is explained with simple instructions and hands on experiments in Chapter 5 The MSA core uses a simple reduce instruction set computer RISC like instruction set for both control and signal processing applications The MSA also comes with a set of multifunction instructions that allows different sizes of op codes to be combined into a single instruction Therefore the programmer has the flexibil ity of reducing the code size and at the same time maximizing the usage of avail able resources In addition some special instructions support video and wireless applications This chapter introduces some basic features of programming and debugging the MSA core and uses examples and exercises to highlight the important features in the software tools In subsequent chapters we introduce more advanced features of the software tools The MSA core is a fixed point processor It operates on fixed point fractional or integer numbers In contrast to the floating point processors such as the Intel Pentium processors fixed point processors require special attention to manipulating numbers to avoid wrong results or extensive computation errors The concepts of real time implementation using a fixed point processor are introduced and examined in Chapter 6 As explained above the embedded core must be combined with internal and external memories ser
58. tunities for new users to explore embedded signal processing before learning the programming details Therefore instructors can make use of these graphical experiments at the end of each chapter to teach embedded signal processing concepts in foundation engineering courses Preface xiii PART B LEARNING REAL TIME SIGNAL PROCESSING WITH THE BLACKFIN PROCESSOR A BITE SIZE APPROACH TO SAMPLING REAL TIME EXAMPLES AND EXERCISES Part B consists of Chapters 5 6 7 and 8 which concentrate on the design and implementation of embedded systems based on the Blackfin processor Unlike a conventional user s manual that covers the processor s architecture instruction set and peripherals in detail we introduce just enough relevant materials to get started on Blackfin based projects Many hands on examples and exercises are designed in a step by step manner to guide users toward this goal We take an integrated approach starting from algorithm design using MATLAB with floating point simu lations to the fixed point implementation on the Blackfin processor and interfacing with external peripherals for building a stand alone or portable device Along this journey to final realization many design and development tools are introduced to accomplish different tasks In addition we provide many hints and references and supplement with many challenging problems for students to explore more advanced topics and applications Part B is in fact bridging the
59. ures and Algorithms of Adaptive Filters 139 4 4 2 Design and Applications of Adaptive Filters 142 4 4 3 More Hands On Experiments 148 4 5 Adaptive Line Enhancer Using Blackfin Simulator 151 4 6 Adaptive Line Enhancer Using Blackfin BF533 BF537 EZ KIT 152 47 Adaptive Line Enhancer Using LabVIEW Embedded Module for Blackfin Processors 155 4 8 More Exercise Problems 158 Part B Embedded Signal Processing Systems and Concepts 5 Introduction to the Blackfin Processor 163 5 1 The Blackfin Processor An Architecture for Embedded Media Processing 163 5 1 1 Introduction to Micro Signal Architecture 163 5 1 2 Overview of the Blackfin Processor 164 5 1 3 Architecture Hardware Processing Units and Register Files 165 5 1 4 Bus Architecture and Memory 182 5 1 5 Basic Peripherals 187 5 2 Software Tools for the Blackfin Processor 189 5 2 1 Software Development Flow and Tools 189 5 2 2 Assembly Programming in VisualDSP 191 5 2 3 More Explanation of Linker 195 5 2 4 More Debugging Features 198 5 3 Introduction to the FIR Filter Based Graphic Equalizer 200 5 4 Design of Graphic Equalizer Using Blackfin Simulator 202 5 5 Implementation of Graphic Equalizer Using BF533 BF537 EZ KIT 206 5 6 Implementation of Graphic Equalizer Using LabVIEW Embedded Module for Blackfin Processors 211 5 7 More Exercise Problems 214 Real Time DSP Fundamentals and Implementation Considerations 217 6 1 Number Formats Used in the Blackfin Processor 2
60. using VDK ce TCP IP Stack application using LwIP and YDK Figure 1 13 Project Wizard window Project Options for exp1_2 Upy Project i Project Eh General amp fis Compile E General 1 fe General 2 E Preprocessor Eh Processor 1 E Processor 2 fea Warning Eh Workarounds Eh Assemble a f Link Eh General Eh LDF Preprocessing Eh Elimination E Processor fa Load Eh Options Eh Kernel Eh Splitter E Pre build Moen se ar Figure 1 14 Project Options dialog box Target Processor Type Name Tool Chain Compiler Assembler Linker Loader Splitter Settings for configuration ADSP BF533 Revision Automatic Executable file expl_2 C C Compiler for Blackfin Blackfin Family Assembler Blackfin Family Linker Blackfin Family Loader Debug 1 4 More Hands On Experiments 17 Code Generation Enable optimization 100 C Interprocedural optimization C Automatic inlining Optimize for code size speed Generate debug information Size Speed Generate assembly code annotations Figure 1 15 Project wizard option for compile Plot Configuration PR Data sets Plot Type Line Plot v Title Untitled Data Setting Name Data Set1 Memory BLACKFIN Memory v Address a s Offset fo Add Count 20 Row count fo Stride 1 Column count ot TT
61. witch to the LabVIEW block diagram shown in Figure 1 19 which contains the source code of the program The dot product is implemented by passing two vectors or one dimensional arrays to the Dot Product function The result is then displayed in the Dot Product Result indicator The value is also passed to the standard output buffer because controls and indicators are only available in JTAG debug or instrumented debug modes The graphical LabVIEW code executes based on the principle of data flow in this case from left to right This graphical approach to programming makes this program simple to implement and self documenting which is especially helpful for larger scale applications Also note the use of the Inline C Node which allows users to test existing C code within the graphical frame work of LabVIEW Now run the program by clicking on the Run arrow to calculate the dot product of the two vectors The application will be translated linked compiled and deployed to the Blackfin processor Open the Processor Status window and select Output to see the numeric result of the dot product operation Another feature available for use with the LabVIEW Embedded Module for Blackfin Processors is instrumented debug mode which allows users to probe wires on the LabVIEW block diagram and interact with live updating front panel controls and indicators while the code is actually running on the Blackfin Instrumented debug can be accomplished through TCP

Embedded Signal Processing with the Micro Signal

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