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Thread: Audio Library and 4096 point FFT on Teensy 3.6

  1. #76
    Thanks a lot for your information, defragster.

  2. #77
    Thank you for your advise, I shall try that after I got the Teensy 4.0 and would let you know the test result.

  3. #78
    Hi Derek,
    I am back to the ZoomFFT after playing around with the FFT4096.
    I have done the following:

    Instead of using single frequency, I fitted a potentiometer to adjust the frequency of the sinewave. The variable sinewave is connected to your AudioGrabberReal256, the waveform can be displayed on the Serial Plotter via the AudioGrabberReal256.

    At the same sketch, I added a fft256 and connect it directly to the sinewave. The transformed values can be displayed on the IDE monitor.

    My target at this stage is to connect the sinewave to the AudioGrabberReal256, and then connect the Grabber to the FFT256. I have tried several methods, and cannot be able to make it work.

    I noticed that your AudioGrabberReal256 doesn't include a output channel. I tried to use the "transmit" function, however, I just cannot be able to make it work. Can you give me some suggestions to tackle this problem?

    Thank you very much for your attention.


  4. #79
    @ DD4WH* #73
    @ DerekR #62

    I finally received my Teensy 4.0 board, and tested your example FFT4096, it works ok. I would like to thank you again for your assistance.

    I am sorry to say that I am new to c/c++, since your example is not a audio stream object, I have to struggle to make it works with other audio stream libraries.

    Same as the AudioGrabber example presented by DerekR in #62, I am still not be able to connect up his grabber to the fft256 yet.

    I shall keep you people inform of the result.


  5. #80
    @ DerekR #62

    I based on your real AudioGrabber256 example posted in your #62 to make up a Teensy Sketch, together with 2 x "arm_rfft_fast_f32" and 2 x "arm_cmplx_mag_f32", all set to fft256. The sketch seems to work ok in Teensy 4.0, however when I was trying to test the performance of the sketch, I found a problem.

    Firstly, I used the AudioSynthNoiseWhite library. However, the sketch only gave one set of result and stopped. After loading the sketch, the Teensy auto loader stopped auto load and every time after that I have to press the manual loading button. I tried a lot of time trying to identify the problem, but not successful.

    I finally tried to use the AudioSynthNoisePink library and AudioSynthWaveformSine library instead. Surprisingly, both of them work ok with my sketch. Not even affecting the auto loader.

    Since the sketch works with both AudioSynthNoisePink and AudioSynthWaveformSine but not with AudioSynthNoiseWhite, I therefore suspected there is a bug in the AudioSynthNoiseWhite library. I should be grateful if you could have a look. If you also found the same problem, please consider reporting to Paul for his attention.

    Thank you very much for your patience.

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