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DISP-2003_ Introduction to Digital Signal Processing

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DISP-2003_ Introduction to Digital Signal Processing Powered By Docstoc
					INTRODUCTION TO
  Microprocessors

    Dr. Hugh Blanton

    ENTC 4337/5337
                        Objectives

• Build intuition for signal processing
  concepts
• Translate signal processing concepts into
  real-time digital communications software
  in laboratory




 Dr. Blanton - ENTC 4337 - Introduction   2
             General Information

  • Contact Information
      • Email—blanton@etsu.edu
      • Phone—(423) 439-4177
  • Web Page
      • http://faculty.etsu.edu/blanton
  • Office Hours
      • MWF—10:15-11:45


Dr. Blanton - ENTC 4337 - Introduction    3
                            Grading

• Calculation of numeric grades
  •    15% midterm #1
  •    25% final #2 (semi-cumulative)
  •    20% homework
  •    50% laboratory




 Dr. Blanton - ENTC 4337 - Introduction   4
  • Laboratory component
      • Students work in teams of two on lab
        assignments/reports
      • Assign team members same lab report
        grade and then apply individual
        deductions for attendance/participation
      • Lowest lab report dropped




Dr. Blanton - ENTC 4337 - Introduction    5
             Academic Integrity

• Homework/Exam assignments
  • Discuss homework/exam questions with
    others
  • Be sure to submit your own independent
    solution
  • Turning in two identical (or nearly identical)
    homework sets is considered academic
    dishonesty




 Dr. Blanton - ENTC 4337 - Introduction     6
  • Laboratory reports
      • Should only contain work of those
        named on report
      • If any other work is included, then
        reference source
      • Copying information from another
        source without giving proper reference
        and quotation is plagiarism
      • Source code must be original work

Dr. Blanton - ENTC 4337 - Introduction    7
                              Topics

  • The TMS320C6X (1 week)
      • Programming (4 weeks)
           •C
           • Code Composer
           • Assembly Language
      • Hardware (4 weeks)
           • architecture




Dr. Blanton - ENTC 4337 - Introduction   8
  • Applications
      • FIR Filters
      • IIR Filters
      • Fast Fourier Transforms




Dr. Blanton - ENTC 4337 - Introduction   9
             TMS320C6x Manuals

  • You need to refer to various TMS320C6000
    manuals, which are only available
    electronically:
      • Code Composer User’s Guide
           • http://focus.ti.com/lit/ug/spru301c/spru301c.pdf
      • Optimizing C Compiler
           • http://www-s.ti.com/sc/psheets/spru187k/spru187k.pdf
      • Programmer’s Guide
           • http://www-s.ti.com/sc/psheets/spru198g/spru198g.pdf
      • CPU and Instruction Set Reference Guide
           • http://www-s.ti.com/sc/psheets/spru189f/spru189f.pdf


Dr. Blanton - ENTC 4337 - Introduction                          10
                  Microprocessors

  • General-purpose processors or
    microcontrollers (GPPs/MCUs for
    short) are either
      • not specialized for a specific kind of
        applications (in the case of general-
        purpose processors), or
      • they are designed for control-oriented
        applications (in the case of
        microcontrollers).



Dr. Blanton - ENTC 4337 - Introduction       11
        Digital Signal Processors

  • DSP processors have features designed to
    support high-performance, repetitive,
    numerically intensive tasks.
  • Mostly designed with the same few basic
    operations in mind
      • They share the same set of basic characteristics
      • These characteristics fall into three categories:
           • specialized high speed arithmetic
           • data transfer to and from the real world
           • multiple access memory architecture


Dr. Blanton - ENTC 4337 - Introduction                  12
                     DSP Features

  • Features that accelerate performance in DSP
    applications include:
      • Single-cycle multiply-accumulate (MAC) capability;
           • high-performance DSPs often have two multipliers that
             enable two multiply-accumulate operations per instruction
             cycle;
               • some DSP have four or more multipliers
      • Specialized addressing modes, for example,
           • pre- and post-modification of address pointers,
           • circular addressing, and
           • bit-reversed addressing




Dr. Blanton - ENTC 4337 - Introduction                         13
                     DSP Features

      • Most DSPs provide various configurations of
        on-chip memory and peripherals tailored for
        DSP applications.
           • DSPs generally feature multiple-access memory
             architectures that enable DSPs to complete several
             accesses to memory in a single instruction cycle
      • Specialized execution control.
           • Usually, DSP processors provide a loop instruction
             that allows tight loops to be repeated without
             spending any instruction cycles
               • for updating and testing the loop counter or
               • for jumping back to the top of the loop




Dr. Blanton - ENTC 4337 - Introduction                          14
                     DSP Features

      • DSP processors are known for their irregular instruction
        sets, which generally allow several operations to be
        encoded in a single instruction.
           • For example, a processor that uses 32-bit instructions may
             encode
               • two additions,
               • two multiplications, and
               • four 16-bit data moves into a single instruction.
           • In general, DSP processor instruction sets allow a data
             move to be performed in parallel with an arithmetic
             operation.
               • GPPs/MCUs, in contrast, usually specify a single operation
                 per instruction




Dr. Blanton - ENTC 4337 - Introduction                               15
                     DSP Features

  • It is worth noting that the difference
    between DSPs and GPPs/MCUs is
    fading:
      • many GPPs/MCUs now include DSP
        features, and DSPs are increasingly adding
        microcontroller features.




Dr. Blanton - ENTC 4337 - Introduction       16
                  What is a DSP?

  • Digital Signal Processors (DSP) process digital
    signals
      • An alternative method to process analog world
        signals

                  ADC              DSP     DAC

      • Once the signal is in digital form, the DSP can
        easily process it
      • After the DSP has processed the signal, the output
        signal must be converted back to analog so that we
        can sense it.

Dr. Blanton - ENTC 4337 - Introduction               17
                         Why DSP?

  • Advantages of digital signal processing
      • Programmability—one hardware does many tasks
      • Flexibility and upgradeability—develop a new code
      • Repeatability—A CD player always plays the same music
        quality
  • Advantages of analog signal processing
      • low cost in some applications—attenuators, amplifiers
      • wide bandwidth (GHz)
      • Infinite resolution (no quantization error) and low signal levels




Dr. Blanton - ENTC 4337 - Introduction                         18
                   The DSP System

  • DSP chip
      • Arithmetic Logic Unit (ALU)
                                         Memory
      • TMS320C6X
  • Memory
  • Converters
                                   ADC    DSP          DAC
      • Analog-to-Digital
      • Digital-to-Analog
  • Communication Ports
      • Serial                            Ports
      • Parallel


Dr. Blanton - ENTC 4337 - Introduction            19
                   Review: Signals

  • Continuous-time (analog) signals are
    functions of a real argument
      • x(t) where t can take any real value
  • Discrete-time (digital) signals are functions of
    an argument that takes values from a discrete
    set x[n]
      • n {...-3,-2,-1,0,1,2,3...}
      • Integer index n instead of time t for discrete-time
        systems
  • Value for x may be real or complex

Dr. Blanton - ENTC 4337 - Introduction                20
       Analog and Digital Signals

  • Amplitude of an analog signal can take
    any real or complex value at each time
    (sample)



  • Amplitude of a digital signal takes
    values from a discrete set
                                         1

                                         1
Dr. Blanton - ENTC 4337 - Introduction        21
       Analog and Digital Signals

  • A system is a transformation from one signal
    (called the input) to another signal (called the
    output or the response).
      • Continuous-time systems with input signal x and
        output signal y (a.k.a., the response):
           • y(t )  x(t )  x(t  1)
           • y (t )  x 2 (t )
      • Discrete-time system examples
           • y[n]  x[n]  x[n  1]
           • y[ n]  x [n]
                      2




Dr. Blanton - ENTC 4337 - Introduction             22
               Audio Compact Discs

  • Human hearing is from about 20 Hz to 20 kHz
  • Sampling theorem: sample analog signal at a rate of
    more than twice the highest analog frequency
      • Apply a lowpass filter to pass frequencies up to 20 kHz;
           • e.g. a coffee filter water (small particles) through a coffee
             filter but not coffee grounds (large particles)
      • Lowpass filter needs 10% of maximum passband frequency
        to roll off to zero (2 kHz rolloff in this case).
      • Sampling at 44.1 kHz captures analog frequencies that are
        less than 22.05 kHz




Dr. Blanton - ENTC 4337 - Introduction                                 23
          Signal Processing Systems

  • Speech synthesis and speech recognition
  • Audio CD players
  • Audio compression (MP3, AC3)
  • Image compression (JPEG, JPEG 2000)
  • Optical character recognition
  • Video CDs (MPEG 1)
  • DVD, digital cable, and HDTV (MPEG 2)
  • Wireless video (MPEG 4/H.263)

Dr. Blanton - ENTC 4337 - Introduction        24
            Communication Systems

  • Voiceband Dialup/Fax modems
  • Digital subscriber line (DSL) modems
      • ISDN: 144 kilobits per second (kbps)
      • Business/symmetric: HDSL and HDSL2
      • Home/symmetric: ADSL and VDSL
  • Cable modems
  • Cell phones
      • First generation (1G): AMPS
      • Second generation (2G): GSM, IS-95 (CDMA)
      • Third generation (3G): cdma2000, WCDMA


Dr. Blanton - ENTC 4337 - Introduction              25
               DSP Architectures

  • Multiply-Add-Accumulate (MAC) instruction
      • Most common operation in DSP,
           • A=B*C+D
      • Typically 70 clock cycles with ordinary processors
      • Single instruction cycle
  • Havard architecture
      • Separate data memory/bus and program memory/bus
      • Multiple memory accesses per instruction cycle
  • Modified von Neuman architecture
      • multiple memory accesses per instruction cycle by the
        simple trick of running the memory clock faster than the
        instruction cycle.



Dr. Blanton - ENTC 4337 - Introduction                   26
               DSP Architectures

  • Deterministic interrupt service routine
    latency
  • Special addressing modes supported in
    hardware
      • Modulo addressing for circular buffers (e.g. FIR
        filters)
      • Bit-reversed addressing (e.g. fast Fourier
        transforms)
  • DSP needs a program that is a series of
    instructions that perform certain functions.


Dr. Blanton - ENTC 4337 - Introduction           27
                     Digital          vs     Analog
                     Digital Signal Processing

       Advantages                                       Limitations

• More flexible.                           • A/D & signal processors speed:
                                             wide-band signals still difficult to
• Often easier system upgrade.               treat (real-time systems).
• Data easily stored.                      • Finite word-length effect.
• Better control over accuracy             • Obsolescence (analog
  requirements.                              electronics has it, too!).
• Reproducibility.




  Dr. Blanton - ENTC 4337 - Introduction                            28
 Impact of DSP on Modern Living
           Cellular/mobile telephony                    Digital audio
           Speech and channel coding                    Stereo and surround sound
           Voice and data processing                    Audio equalization and
           Power management                             mixing
           Multipath equaliztion                        Electronic music


                                                        Medical electronics
             Automotive
                                                        Critical/intensive care
             Digital Audio
                                                        monitors
             Digital Radio
                                                        Digital X-rays
             Personal communication
                                                        ECG analyzers
             systems
                                                        Cardiac monitors
             Active suspension
                                                        Medical imaging


                         Personal computer
                         Sound cards
                         Data storage and retrieval
                         Error correction/concealment
                         Multimedia
                         Modems



Dr. Blanton - ENTC 4337 - Introduction                               29
                         Analog & digital signals
                         Analog                                                                Digital
               Continuous function V of                        Discrete function Vk of
               continuous variable t (time,                    discrete sampling variable tk,
               space etc) : V(t).                              with k = integer: Vk = V(tk).


              0.3                                                          0.3
              0.2                                                          0.2




                                                             Voltage [V]
Voltage [V]




              0.1                                                          0.1
                0                                                            0
              -0.1                                                         -0.1             ts ts
              -0.2                                                         -0.2
                     0   2      4    6   8     10                                 0     2     4    6     8    10
                             time [ms]                                                               t
                                                                                      sampling time, k [ms]

                                             Uniform (periodic) sampling.
                                             Sampling frequency f S = 1/ tS

              Dr. Blanton - ENTC 4337 - Introduction                                                 30
                 DSP: aim & tools
                 • Predicting a system’s output.
Applications     • Implementing a certain processing task.
                 • Studying a certain signal.



                 • General purpose processors (GPP), -controllers.
Hardware         • Digital Signal Processors (DSP).       Fast          real-time
                                                          Faster         DSPing
                 • Programmable logic ( PLD, FPGA ).


                 • Programming languages: Pascal, C / C++ ...
Software         • “High level” languages: Matlab, Mathcad, Mathematica…
                 • Dedicated tools (ex: filter design s/w packages).


  Dr. Blanton - ENTC 4337 - Introduction                           31

				
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