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Aim


To perform the 4 point DFT process from a given discrete sequence in TMS320C6745 KIT


Requirements


 
Theory

The sequence of N complex numbers x0, ..., xN-1 is transformed into another sequence of N complex numbers according to the DFT formula:

dft 4 point formula

It transforms one function into another, which is called the frequency domain representation, or simply the DFT, of the original function (which is often a function in the time domain).


The DFT requires an input function that is discrete. Such inputs are often created by sampling a continuous function, such as a person's voice. The discrete input function must also have a limited (finite) duration, such as one period of a periodic sequence or a windowed segment of a longer sequence. Unlike the discrete time Fourier transform (DTFT), the DFT only evaluates enough frequency components to reconstruct the finite segment that was analyzed. The inverse DFT cannot reproduce the entire time domain, unless the input happens to be periodic. Therefore it is often said that the DFT is a transform for Fourier analysis of finite-domain discrete-time functions.


Procedure

1. Open Code Composer Studio v4 .


2. In WorkSpace Launcher.


  • BROWSE → Select the project location and make one new folder, MAKE NEW FOLDER → Type the Workspace name, OK → OK.

3. FILE ⇒ NEW ⇒ CCS PROJECT


  • Project name: Type your project name.
  • Tick use default location. → NEXT
  • Project type C6000.
  • Tick Debug And Release. → NEXT → NEXT.
  • Output type: Executable.
  • Device Variant : generic - TMS320C6745.
  • Device Endianness : little
  • Code Generation Tools: TI v6.1.12.
  • Run time support library: automatic.
  • Target content: none. →FINISH

4.FILE ⇒ NEW ⇒ SOURCE FILE

  • Source file: Type your projectname.c( .c extension is must ).
  • Type the program.
  • FILE → SAVE.

5. Paste the following board library files in workspace location.


  • Common folder (contains header files)
  • Gel folder (contains gel file)
  • Library folder(contains library files)

6. Paste the Linker file in the project location.(linker file is available in cd)


Note: Those folders and linker file are availble at cd.


7. PROJECT ⇒ PROPERTIES ⇒ C/C++ BUILD → BASIC OPTION


  • Target processor version(--silicon version, -mv)    :   6400+ OK.
  • IN C/C++ BUILD, INCLUDE OPTIONS (Add dir to #include search path(--include_path,-I)) select this add icon add iconand add the following three path by indivdually
       -  "${Diag}../../common/header"
       -  "${XDAIS_CG_ROOT}/packages/ti/xdais"
       -  "${C6000_CSL_CG_ROOT}/include"

8. FILE ⇒ NEW ⇒ TARGET CONFIGURATION FILE


  • file name: projectname. ccxml (.ccxml extension is must)
  • Connection: Texas Instrument XDS100 v1 USB Emulator.
  • Device:TMS320C6745. (Tick the TMS320C6745)→ SAVE → TARTGET CONFIGURATION → C674X_0 → BROWSE, browse the workspace location, open the gel folder and select the GEL file. → OPEN → SAVE.

9. In C/C++ Project window, Right click the project ⇒ REBUILD PROJECT.


10. Connections


  • Connect the usb cable, PC to TMS320C6745 KIT.
  • Connect the 5v adapter.
  • Power on the kit.

11. TARGET ⇒ DEBUG ACTIVE PROJECT.


12. View ⇒ memory


  • Enter An Address: 0xC0001000 → Enter.
  • Type the input.
    For example:
    0xC0001000 – 0x0001
    0xC0001004 – 0x0001
    0xC0001008 – 0x0001
    0xC000100C – 0x0000
    

13. Debug ⇒ Run.


14. Debug ⇒ Halt


15. See the output at following location,


View memory


    • Enter An Address: 0xC0001030 → Enter.
    • For example:
0xC0001030 – 0x0003
0xC0001030 – 0x0000
0xC0001030 – 0x0001
0xC0001030– 0x0000

16. View ⇒ memory


    • Enter An Address: 0xC0001050 Enter.
      For example:
0xC0001050 – 0x0000
0xC0001054 – 0xFFFF (-1)
0xC0001058 – 0x0000
0xC000105C – 0x0001

Program
#include "c6745.h"

#include 

#define  PI     180

#define N      4

 

float Real_coeff[16] = {1.0,1.0,1.0,1.0,

                                                1.0,0.0,-1.0,0.0,

                                                1.0,-1.0,1.0,-1.0,

                                                1.0,0.0,-1.0,-1.0};

 

float Imag_coeff[16] = {0.0,0.0,0.0,0.0,

                                                0.0,-1.0,0.0,1.0,

                                                0.0,0.0,0.0,0.0,

                                                0.0,1.0,0.0,0.0};                                          

 

void main()

{

        int *Input,*Real_out,*Imag_out;

        int i=0,j=0,k=0;

        float real_temp=0,imag_temp=0;

       

        Input = (int *)0xC0001000;

        Real_out = (int *)0xC0001030;

        Imag_out = (int *)0xC0001050;

 

        for(i=0;i<4;i++)

        {

                real_temp=0;

                imag_temp=0;

 

                for(j=0;j<4;j++)

                {

                        real_temp += (Input[j] * Real_coeff[k]);

                        imag_temp += (Input[j] * Imag_coeff[k]);

                        k++;

                }

 

                *(Real_out + i) = (int)real_temp;

                *(Imag_out + i) = (int)imag_temp;

 

        }

 

        while(1);

}
Result

Thus, the 4 point DFT of given discrete sequence has performed and the result is stored at memory location(0xC0001030 & 0xC0001050).