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CCS/TMS320F28377D: Application problem (C28X-VCU-LIB-UG) of VCU-II

garin zhu
Intellectual 360 points
Part Number: TMS320F28377D
Other Parts Discussed in Thread: C2000WARE

Tool/software: Code Composer Studio

There are the following questions when using C2000 TMS320F28377D . Can you help me, thank you!           

In the Fast Fourier Transform (C28X-VCU-LIB-UG) of VCU-II, FFT data structure is defined as follows:          

  Typedef struct           

{         

Int16_t *pInBuffer;           

Int16_t *pOutBuffer;          

Const int16_t *pTwiddleFactors;         

Int16_t nSamples;           

Int16_t nStages;           

Int16_t twiddleSkipStep;           

Void (*init) (void *);          

Void (*run) (void *);         

   }           

_CFFT_Obj_           

There are the following questions:          

1.  What is the data structure of the incoming pInBuffer when using CFFT? Is plural real number + imaginary number or other structure?           

2.Is the data structure using pOutBuffer output the same as the input structure?        

3. is there any other detailed information about the use of Lib?                  

  • 0
    TI__Intellectual 835 points

    Hi Garin,

    Thanks for your query. To get a better understanding of these questions, I would like you to go through an example which can be found here:

    <install_dir>\C2000Ware_1_00_03_00\libraries\dsp\VCU\c28\examples\fft\2837x_vcu2_cfft_32

    -Ritvik

  • 0 in reply to Ritvik Sadana1
    Intellectual 360 points
    You say download C2000ware to see the routine, have seen, and the difference is not much, now the problem is that the results calculated in the <install_dir>\C2000Ware_1_00_03_00\libraries\dsp\VCU\c28\examples\fft\2837x_vcu2_cfft_32 example is completely different from the MATLAB, what is the specific reason?
  • 0
    TI__Mastermind 20850 points

    garin zhu said:
    1.  What is the data structure of the incoming pInBuffer when using CFFT? Is plural real number + imaginary number or other structure?   

    The data should be organized real then imaginary

    pInBuffer[0] = Re[0]

    pInBuffer[1] = Im[0]

    pInBuffer[2] = Re[1]

    pInBuffer[3] = Im[1]

    and so on and so forth

    garin zhu said:
    .Is the data structure using pOutBuffer output the same as the input structure?

    pOutBuffer and pInBuffer should not point to the same location. This algorithm does not work in-place, its an off place algorithm, i.e. at the end of each stage the input for the current stage becomes the output for the next stage, and the output of the current stage becomes the input to the next stage.

    garin zhu said:
    . is there any other detailed information about the use of Lib?      

    The library comes with a user's guide and plenty of examples for each module.