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I have a RPi and attached to an input pin I have an ADC (MCP3002) and an op-amp (MCP601) and a piezo element connected to them. The RPi reads the input pin, gets the digital data and at the moment generates a graph using Matplotlib.

I want to take this data and store it in a meaningful way so I can analyse the input from the piezo and determine the frequency of the vibration. I understand I may need to use a codec (not sure how to develop using this) and to get the data I plan on using FFT algorithm to establish the frequencies present. The code I have used is an adaptation of the code found here

The voltage generated is digitized and converted to it's digital number equivalent and plotted on a graph to generate a waveform graph. I just want to convert it to a WAV file or something that can be analysed effectively using FFT.

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If you are using matplotlib, then you are using Python, correct? If so, then for FFTs, you'll likely want to look at scipy or numpy.

For generating WAV files, Python includes a library called wave that can generate wave files from raw samples.

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  • I've also been on a raspberry pi forum and it's been suggested that I could use CSV format and find a FFT algorithm to analyse raw values
    – DonnellyOverflow
    Commented Oct 6, 2015 at 15:27
  • If your values were in CSV format, you could read the values into Python (csvreader is a Python library), and then use numpy or scipy to do the FFTs. But there's certainly also many programs that can just read in and display an FFT from a CSV (it's even something you could do in Excel (I think with a plugin)).
    – Brian
    Commented Oct 6, 2015 at 16:31

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