I have added a third axis to the spectrum analyzer. The atMega328 (Arduino Nano) program is adxl335_3can_01_en.c. The Python 2.7 program is fft_spectrum_gui_3can.py.

I also made a version of the three axis analyzer that works with Python 3.5, fft_spectrum_gui_3can_py3_01.py.

There is also a file with sampled data for testing purposes datos_3can_20-12-2016__11_39_50.txt. Works with both versions of the 3 axis FFT analyzer.

Notice that the accelerometer Z axis is limited to 500 Hz.

This files are also available on GitHub at https://github.com/ariquezada/FFT-spectrum-analyzer/tree/master/3_axis.

The screen shot is shown below.