CCS/TMDSEVM6678: Plot FFT - Difference between FFT plot and single plot

Nivaldo,

There is a chance the parameter "Sampling Rate Hz" is not properly set.

For details, check the topic Graphs of the CCS online help. Go to menu Help --> Help Contents --> search for "Graph"

Hope this helps,
Rafael

Hi Rafael.

my Fs is 4000Hz

my code

Fs = 4000; // Sampling frequency
T = 1/Fs; // Sample time
L = points; // Length of signal
freq1 = 100;
for(x = 0; x < L; x++)
t[x] = T*x;

for(x = 0; x < L; x++)
     y[x] = sin(2*pi*freq1*t[x])/((float)1.0*L);

 gen_twiddle_fft32x32(w_32x32, NPT, 2147483647.5);

in_32x32 is complex from y

 DSP_fft32x32(w_32x32, NPT, in_32x32, out_32x32);

What do you think, any mistke?

Nivaldo,

Thanks for sending the screenshot; If you don't mind, could you export the ytemp variable contents to a .dat file? This way I could try to reproduce this issue here.

In the meantime I will try to get an example running here. Which one are you using? Is it the fft_ex with a single sinewave?

Regards,
Rafael

Hi Rafael,

yes the fft_ex I have tried the fft_sp_ex too, but i got the same. 

here the dat files.

ytemp.dat

y.dat