real-time dsp for educators

8/12/2019 Real-Time DSP for Educators

1/48


2/48

Agenda

Introduction

Motivation

DSK and Software Installation

Building Real-Time DSP Applications

Software Organization

Building a CCStudio Talk-Through Application

FIR Filtering Signal Generation

Advanced Topics

DSP/BIOS Application

HPI Daughtercard (DSP Services/Host Services)

Individual Projects

Wrap-Up


3/48

Motivation

Do you teach or want to teach a DSPcourse?

Do you use MATLAB exercises in yourcourses?

Do you assign exercises that work with

actual signals (not generated in MATLAB)? Do you include real-time DSP

demonstrations in your courses?

Do you assign real-time projects?


4/48

Real-time DSP It can be a real struggle to get started with

real-time DSP

Lots of details come up that just arent an issue

when programming in a workstation environment

Documentation is written for experts

Learning curve is steep, if not vertical!

Few understandable examples are available Complexity is the norm

On-line and seminar style training is available

directly from TI and the third party vendors But, most of this training is not appropriate for the

typical student (or educator) due to at least one of

the following issues


5/48

Typical Training Issues Not meant for educators Our first courses should motivate our students to

learn more about real-time DSP

Much of the industry does not do sample-by-

sample DSP, despite the fact that few teach

anything else

Meant for DSP experts Expects significant familiarity with DSP system

design

Intended for engineers transitioning from otherDSP targets

Usually introducing the latest innovations and

technologies, not fundamentals


6/48


7/48

The DSP Big Picturey[n] = ...

differenceequation

H(z)transferfunction

H(ej)frequencyresponse

h[n]impulse

response

pole/zerodiagram

blockdiagram


8/48

The Real-time DSP Big Picturey[n] = ...

differenceequation

H(z)transferfunction

H(ej)frequencyresponse

h[n]impulse

response

pole/zerodiagram

blockdiagram

real-time

implementation


9/48

DSP of Analog Signals

antialiasingfilter

sampleandhold

DSPdigital

to analogconverter

analog todigitalconverter

reconstructionfilter

analogworld

analogworld


10/48


11/48

Agenda Introduction

Motivation





FIR Filtering Signal Generation

Advanced Topics



Individual Projects

Wrap-Up


12/48

Hardware Discussion

Lets unpack our DSKs

Look at what comes in your box

Note that like many USB devices, the

hardware installation comes AFTER thesoftware installation

A quick tour of the board


13/48

DSK Overview

TMS320C6713 DSP at 225MHz

TLV320AIC23 stereo codec Microphone & line inputs

Headphone & line outputs

Uses both McBSPs We configure for 16-bits at 48KHz

16MB SDRAM / 512KB Flash memory

Onboard USB-based JTAG emulator 4 DIP switches & 4 LEDs (user controlled)


14/48

DSK Overview (continued) Three daughtercard connectors

J1 HPI interface

New to the C6713 DSK Used by the Educational DSP HPI daughtercard

Direct DSP control from a host computer

DSP can use daughtercard for communications (USB/RS-

232), digital I/O, and analog inputs

J3 Peripheral Interface

McBSPs, Timers

J4 EMIF (parallel memory bus)

SDRAM, Flash Memory

Many EVMs and daughtercards are available

from TI and others


15/48

TI TMS320C6713 DSK


16/48

TI TMS320C6713 DSK


17/48

DSK w/ HPI Daughtercard


18/48

Software Installation Quick Start Installation Guide

CCStudio software installation

Follow the CDs instructions

Do not attempt to register the software at this time

Be sure to install both CCStudio 3.1 and the C6713 DSK target

content. Leave the CD in after the install finishes and then connect the

DSK to install the USB driver.

Note that there are two CCStudio icons on the Desktop

The C6713 icon will automatically import the DSK into CCStudio. winDSK6

A quick look at the contents of the textbook CD-ROM


19/48


20/48

Our Software Organization All software is interrupt-driven

All configuration code is contained in acommon_code directory

All applications are designed to run on both the

C6713 DSK and the TMS320C6711 DSK (withthe onboard codec and several codec

daughtercards)

A single #define selects the proper software toconfigure the codec, the input source, and the

sampling rate


21/48

A Basic Application(Talk-through)


22/48

Agenda Introduction

Motivation


Building Real-Time DSP Applications Software Organization


FIR Filtering

Signal Generation

Advanced Topics



Individual Projects

Wrap-Up


23/48

The CCStudio Project Big Picture Open CCStudio Create a project

Be aware of what directory you are in, especially ifyou then navigate somewhere within CCStudio

Add files to the project directory

Add files to project Our code is interrupt driven, so most work today

will be done on isrs.c

Setup the compiler options

Build the project Load the project

Run the project


24/48


25/48

CCStudio Observations Does the talk-through program work? You can run or halt the program at

anytime and you dont need to reload

You can establish a watch window by

highlighting and right-clicking on thevariable that you selecting, then selecting

Add to Watch Window

Watched variables can be modified whilethe program is running (if they are in

scope)


26/48

A Few Comments Watch window(s)

Make sure that you are in scope

The volatile keyword

Function prototypes and return types

ISRs and the run-time schedule Sample-by-sample processing

Gain adjustments (volume control)

Hello, world can we print to the host PC?

Turning the user LEDs on and off


27/48

Agenda Introduction

Motivation


Building Real-Time DSP Applications Software Organization


FIR Filtering

Signal Generation

Advanced Topics



Individual Projects

Wrap-Up


28/48

FIR Filtering FIR filters are the most popular type of

digital filter Always stable

Easy to design Easy to ensure linear phase response

Require more coefficients for same roll off

compared to IIR filters


29/48

FIR Filter

z-1

z-1

z-1

z-1

+

+

+

+

x[n] y[n]b0

b1

b2

b3

b4

x[n-1]

x[n-2]

x[n-3]

x[n-4]


30/48

FIR Difference Equation

[ ] [ ] [ ] [ ]

[ ] [ ] [ ] [ ]

[ ] [ ] [ ]

[ ] [ ] [ ] [ ] [ ] [ ] [ ]

0

0

[ ] *

[ ] *

0

0 0 0 1 1

k

N

k

N

k

y n h k x n k h n x n

y n b k x n k b n x n

y b k x k

y b x b x b N x N

=

=

=

= =

= =

=

= + + +

L


31/48

FIR Difference Equation (cont)

[ ] [ ] [ ] [ ] [ ] [ ] [ ]

[ ] [ ] [ ] [ ] [ ] [ ] [ ]

0 0 0 1 1

but we can modify the indices

0 0 0 1 1

y b x b x b N x N

y b x b x b N x N

= + + +

= + + +

L

L


32/48

CCStudio Implementation Local declaration

Declare the b coefficients in the ISR Cut-and-paste can also work

Additional files (e.g., coeff.c and coeff.h)

Great for large filters

But do you really want to type in all of those

coefficients by hand?

Create the files directly from MATLAB

FIR_dump2c.m


33/48

Sptool Startup GUI


34/48

Fdatool Startup GUI


35/48

More FIR a few ideas Flanging

Chorus Circular buffering

Echo creation Other FIR filter forms

e.g., second order sections

Impulse modulator digital transmitter


36/48

Agenda Introduction

Motivation





FIR Filtering

Signal Generation Advanced Topics



Individual Projects

Wrap-Up

R l ti W f


37/48

Real-time Waveform

Generation Your mission generate a 1 kHz sinusoid

Some ways to do it

VOUT = VMAXsin(2ft)

Calculate directly as a function of t

Calculate as a function of the desired signal phase

Use lookup table to obtain sine values, use index as phase

accumulator

Use complex vector rotation

Use a digital resonator

May want to glance at textbook Modify your talk-through application as necessary create

a sinusoid generator


38/48

Agenda Introduction

Motivation





FIR Filtering




Individual Projects

Wrap-Up


39/48

Intro to DSP/BIOS Software

Kernel Foundation DSP/BIOS kernel is a lean real-time operating

system (RTOS) specific to the TI DSPs

There are advantages and disadvantages tointroducing it into an academic setting

Follow Appendix B of your textbook Section B.1 Introduction

Section B.2 Exercise in using threads Can come back to this if you have time & desire

Section B.5 Talk-through on the C6713 DSK

This is equivalent to the earlier tutorial, but in a DSP/BIOSenvironment

Text for cut-and-paste is on your CD-ROM


40/48

Agenda Introduction

Motivation





FIR Filtering




Individual Projects

Wrap-Up


41/48

eDSP DSK6713HPI Daughtercard Host Services

Using a host PC to control the DSK without CCStudio

winDSK6

MATLAB Interfaces (data acquisition and real-time control)

DSK6X_Control for host application development

DSP Services

The DSP software can use the daughtercard resourcesas well

USB and RS-232 communications

Up to 16 digital I/O pins

Up to 8 analog inputs

Software interface is already provided simple function

calls are used to access all resources


42/48

Agenda Introduction

Motivation





FIR Filtering




Individual Projects

Wrap-Up


43/48

Individual Project Time Have at it!

Feel free to ask questions

A d


44/48

Agenda Introduction

Motivation





FIR Filtering




Individual Projects

Wrap-Up


45/48

Wrap-Up The DSK development environment isfairly easy to use once you know how!

Practice making your own CCStudioprojects

Mikes software page has lots of software

for the C6713 and older DSKs http://eceserv0.ece.wisc.edu/~morrow/software/

For more information on the HPI daughtercard

see the Educational DSP website http://www.educationaldsp.com


46/48

Real-Time DSP for Educators

Michael Morrow ([email protected])

University of Wisconsin-Madison

Thad Welch ([email protected])

United States Naval Academy

Cameron Wright ([email protected])University of Wyoming


47/48

References [1] TMS320C6713 DSK Technical

Reference, Spectrum Digital, Jan. 2004 [2] Digital Signal Processing, a

computer-based approach, Sanjit K.

Mitra, McGraw Hill, 2001 [3] Real-time Digital Signal Processing

from MATLAB to C with the

TMS320C6X, Thad B. Welch,Cameron H. G. Wright, Michael G.Morrow, CRC Press, 2006


48/48

real-time dsp for educators

Documents