hi,
this is my first time using tms320vc5510 dsp board by TI.

i need to process my signal using FFT. thus, i had generated a 12 cycle
sine waveform to test the FFT. i had referred to TMS320C55x DSP Library
Programmer=E2=80=99s Reference (SPRU422i) on how to call the FFT function f=
rom
dsplib but some how the output was not really as desired. i suspect there
was something wrong with my source code.

may anyone teach me or show me some example or any detail technical
document on how to call FFT function from dsplib tms320vc5510 and how
to determine whether the function is perform correctly or not?

thanks for ur help...

=20

Henry Low-

> this is my first time using tms320vc5510 dsp board by TI.
> 
> i need to process my signal using FFT. thus, i had generated a 12 cycle
> sine waveform to test the FFT. i had referred to TMS320C55x DSP Library
> Programmer’s Reference (SPRU422i) on how to call the FFT function from
> dsplib but some how the output was not really as desired. i suspect there
> was something wrong with my source code.

What do you mean "not really as desired" ?  Maybe it's actually working and it's
your
desire that is incorrect :-)

-Jeff

Henry-

> im sorry for the trouble..i would like to ask something...according to
> TMS320VC55x DSP library programmer's reference. it stated that we can
> find examples on how to use every single function in DSPLIB, in the
> examples subdirectory.thus i had opened the project of rfft and run it
> on ccs. this project should be free from trouble.. my question is how
> to verify that this function is working correctly..
> so sorry for the trouble and thank you so much for spending sometime
> to help me..
> thank you once again... =)

Suggestions:

1) First verify cfft function, not rfft.  Start with simplest example first.

2) Create an array of 128 real/imag values, set first real value to 1, remaining real
values to zero.  Set all imag values to zero.  Remember that cfft takes data as
"complex values"; i.e. you need an array of 256 of Re/Im pairs.

3) Run cfft using size 128 (order = 7).

Your results should show all real values 1, all imag values zero (you remember this
from class, right?  What is the frequency response of an impulse?)  The actual output
value won't be "1", it will be 128 due to FFT scaling.  You should also recall this
from class.

You can perform other similar experiments; for example the inverse of above:  set all
real values to 1, all imag to zero.

My overall suggestion:  stop relying on web documents to show you an exact example
for every little thing.  Start relying on what you learned, think about what to
expect (if I do this, then I should get this..).  Be creative and persistent.

-Jeff
One suggestion is to create a
> 
> --- In c...@yahoogroups.com, Jeff Brower <jbrower@...> wrote:
> >
> > Henry Low-
> >
> > > this is my first time using tms320vc5510 dsp board by TI.
> > >
> > > i need to process my signal using FFT. thus, i had generated a 12
> cycle
> > > sine waveform to test the FFT. i had referred to TMS320C55x DSP
> Library
> > > Programmer’s Reference (SPRU422i) on how to call the FFT
> function from
> > > dsplib but some how the output was not really as desired. i
> suspect there
> > > was something wrong with my source code.
> >
> > What do you mean "not really as desired" ?  Maybe it's actually
> working and it's your
> > desire that is incorrect :-)
> >
> > -Jeff
> >