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fitting FFT into Arduino

by didier on Tue Oct 05, 2010 3:57 am

Has anyone tried to fit an FFT into Aduino?
I am investigating the possibility of adding a frequency analyser probe to my arduino based data logger. Very helpful for diagnosing defective pipes, valves and taps.
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Re: fitting FFT into Arduino

by adafruit_support_bill on Tue Oct 05, 2010 4:54 am

I saw this one a few months ago - (but no source code):
http://qik.com/video/7962341
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Re: fitting FFT into Arduino

by didier on Tue Oct 05, 2010 10:11 am

Thanks arduwino! It looks like the frequency spectrup is reversed (low frequency on the right)...
Any way, I found what I needed, and it is even simpler than the VB.NET code I had to write for that. Pending publication of a PlainFFT libray on my blog :wink:
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Re: fitting FFT into Arduino

by adafruit on Tue Oct 05, 2010 10:17 am

we were just looking into this so you're in luck :)
http://www.arduino.cc/cgi-bin/yabb2/YaB ... 1262129475
see also elmchan's FFT
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Re: fitting FFT into Arduino

by didier on Tue Oct 05, 2010 12:33 pm

Thanks Limor,
I knew about this post. the Goertzel algorithm is very interesting, but I really wanted to get a spectrum representation. I am quite happy with my early code which is quick and compact. I will now refine it with some windowing and release it soon.
I will then probably try a graphic LCD, and add some specific spectrum analysis routines (peak picking, spectrum comparison, etc.)
in a separate library (PlainDSP ? :mrgreen: )
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Re: fitting FFT into Arduino

by adafruit on Tue Oct 05, 2010 2:18 pm

please do, we are really really interested in it
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Re: fitting FFT into Arduino

by didier on Wed Oct 06, 2010 4:52 pm

FFT topic started! http://didier.longueville.free.fr/arduinoos/?p=1022

The first application will consist in a tone decoder (my youngest daughter will be able to fine tune her guitar now!)
Specifications are:
High speed signal sampling (Pending, not an issue at all)
Windowing (Done)
FFT (Done)
Converting complex to real (Done)
Peak picking (Done, simplified version from my Panorama tool box)
Peak apex interpolation (Done)

And again with the least number of extra components :wink:
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Re: fitting FFT into Arduino

by didier on Fri Oct 15, 2010 8:05 am

By the way...

What are you interested in precisely? My pesonnal project is ready now, and I did prepare half a dozen posts which are in the pipe, ready for continuous publication. I would be glad to contribute to your projects as long as I know a little bit more about them :wink:
Kind regards
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Re: fitting FFT into Arduino

by adafruit on Fri Oct 15, 2010 9:37 am

we just wanted to blink some LEDs :D dont worry about it. its a future future project. it just happened we were looking for it.
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Re: fitting FFT into Arduino

by didier on Fri Oct 15, 2010 11:05 am

well... :|
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Re: fitting FFT into Arduino

by adafruit on Fri Oct 15, 2010 1:00 pm

we were going to make a spectrum display on a graphic LCD too. umnm. its not that exciting :(
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Re: fitting FFT into Arduino

by didier on Fri Oct 15, 2010 5:57 pm

I see ! I just ordered a bunch of components including an LCD graphic display... Any hint/ideas/recommandations related to this type of displayshall be welcomed :wink:
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Re: fitting FFT into Arduino

by didier on Tue Oct 19, 2010 7:13 am

The libray shall be issued on publication of the last post on this subject by the end of the week. Next will start an other subject related to repeat acquisitions, so as to say scanning an adc port for wave capture. And next should come a subject on displaying 2D signals and spectra on a graphic LCD. Who did work on that?
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Re: fitting FFT into Arduino

by didier on Tue Oct 26, 2010 9:30 am

Honk honk! Could someone help me gathering links related to grphic LCDs?
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Re: fitting FFT into Arduino

by adafruit on Tue Oct 26, 2010 10:21 am

we have two in our shop. we rather like the serial one but it takes a lot of ram. the KS0108 one is very popular!
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