CrossRoads:
What are you doing with the array im[] ?1/9600 = 104uS, so your 600uS seems a little off.
im[ ] array stands for Imaginary[ ].
I need real number arguments and Imaginary number arguments to put in a fix_fft functions to execute a FFT.
Because i only need the real data i set up 0 into de im array. 128 stands for the numbers of samples.