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# Auto Correlation using TMS320F2812 DSP

Auto Correlation

###### Aim

To perform the Auto Correlation of a given discrete sequence in TMS320F2812 KIT.

###### Theory

Autocorrelation is the cross correlation of a signal with itself. Informally, it is the similarity between observations as a function of the time separation between them. It is a mathematical tool for finding repeating patterns, such as the presence of a periodic signal which has been buried under noise, or identifying the missing fundamental frequency in a signal implied by its harmonic frequencies. It is often used in signal processing for analyzing functions or series of values, such as time domain signals.

In an auto correlation, which is the cross-correlation of a signal with itself, there will always be a peak at a lag of zero unless the signal is a trivial zero signal.

Given a signal , the continuous autocorrelation is most often defined as the continuous cross-correlation integral of with itself, at lag .

where represents the complex conjugate and represents convolution. For a real function, f = f .

###### Procedure

Note: Once you install the Code Composer Studio v 3.3 software, the two icons will display in desktop

• Setup Code Composer Studio v3.3
• Code Composer Studio

1. Open Setup Code Composer Studio v3.3.

2. In System Configuration, select the board then → Remove all → yes.

• In family, select C28xx.
• In platform, select xds100 usb emulator.
• In Endianness, select little.
• Select F2812 XDS100 USB Emulator add save & quit no.

Note: The above two steps only for first time to setup the processor in CCS.

3. Open Code Composer Studio v3.3.

4. Project → New.

• Project name: type the project name.
• Location: Browse, select the project location .
• Project Type: Executable(.out)
• Target: TMS320C28XX. → Finish.

5. File → New → Source file.

• Type the program in untitled window.

File→ Save.

• Browse our project location then type our project name.c ( .c extension is must) → save.

7. Paste the following two cmd files in our project folder.

• F2812_EzDSP_RAM_lnk.cmd
• DSP281x_GlobalVariableDefs.c

1. Project → Add files to project.

In file of type : All files

Ctrl + Select the following files

• projectname.c
• DSP281x_GlobalVariableDefs.c
• F2812_EzDSP_RAM_lnk.cmd

9. Project → Build Option.

In compiler tab, select Preprocessor

• Search path(-i): C:\CCStudio_v3.3\C2000\cgtools\lib
• Incl libraries(-l): rts2800_ml.lib.

• Stack Size(-stack): 0x400 ok.

10. Project → Build (or) Rebuild all.

11. Connections for TMS320F2812 KIT

12. Debug → connect.

13. File → Load Program → Browse and select the projectname.out file → open

14. Debug → Go main.

15. View → memory

Type the input.

For example:

• 0x3F9100 – 0x0001
• 0x3F9101 – 0x0002
• 0x3F9102 – 0x0003
• 0x3F9103 – 0x0004

16. Debug → Run.

17. Debug → Halt.

18. See the output at following location, View → memory

For example:

• 0x3F9200 – 0x0004
• 0x3F9201 – 0x0012
• 0x3F9202 – 0x0020
• 0x3F9203 – 0x0030
• 0x3F9203 – 0x0020
• 0x3F9203 – 0x0012
• 0x3F9203 – 0x0004

###### Program

#include "DSP281x_Device.h"

#define xn 4

#define hn 4

void main()

{

int *xval,*outval,j;

int n,k,i,t[100]={0};

xval = (int *)0x003F9100;  /* input  */

outval = (int *)0x003F9200; /* output */

for(i=0;i<(xn+hn-1);i++)

{

outval[i] = 0;

t[i]=0;

xval[xn+i]=0;

}

for(i=0,j=(hn-1);i<(hn);i++,j--)

t[i] = xval[j];

for(n=0;n<(xn+hn-1);n++)

{

for(k=0;k<=n;k++)

outval[n] = (outval[n])+((xval[k])*(t[n-k]));

}

while(1);

}

###### Result

Thus, the Auto Correlation of a given discrete sequence has performed and the result is stored at memory location(0x3F9200).