EXPERIMENT 3

A DIGITAL SIGNAL OSCILLATOR

written by Neal Glover (nealglover@uky.campus.mci.net)
	   Anthony Reeves (acrv@msg.ti.com)
           Kevin Donohue (donohue@engr.uky.edu)
           University of Kentucky
           Electrical Engineering Department

Date of last revision (10-31-01)

REFERENCES

Digital Signal Processing,
(Ifeachor and Jervis,1993)

DSKD Starter Kit Manual

TMS320CXX Users Guide

EQUIPMENT AND MATERIALS

DSKD Starter Kit and Software

Personal Computer

RS232-C Interface Cable

RCA Jack

9 Vac power supply (for the DSK)

Oscilloscope


INTRODUCTION

This experiment will put knowledge gained from the previous experiments to 
work on practical programming problems.  The primary task is to design a 
digital signal oscillator.

PROCEDURE

1.  With the power turned off, connect your board to the PC RS232-C port on
    the computer. Connect the 9 Vac adapter to the board and plug into an 
    outlet. Turn on the PC and change to the directory containing the 
    program DSKL. 

2.  Determine the inverse Z transform of a system whose impulse response is 
    a sinusoid of frequency f.

3.  To design a filter that will produce a 600Hz sine wave, what should the 
    value of the coefficients be if the sampling frequency is set at 10 kHz ?
 
4.  read the lab3_header.asm, try to understand how it operates.  Calculate
    the coefficients needed to generate the sine wave in question 3 and add
    them in the header file.

5.  write your own SINECAL routine at the end of header file to Implement 
    the mathematics required.  Multiply output by 1000 which is stored at
    onet, then make it an integer and store it in R6.  (the program following
    SINECAL will send out the value in R6). 

    In order to debug your program, try loading the math routine into the 
    DSP without sending any data to the AIC, that is, you can write a seperate code
    and make sure it generate the expected sequence before you put them 
    into the routine SINECAL.  This will allow the use of the debugger without 
    interrupt hassles and allow easy comparison between actual results and 
    expected ones.

6.  Now,run the program and observe the output of the DSK on 
    an oscilloscope.  Does it appear to be a good sine wave?  Is the 
    frequency correct?  Then Modify your coefficient so it generate 1000Hz
    under sampling frequency of 10kHz with twice the amplitude.  Verify
    them on oscilloscope.