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    Are the 128 samples in one buffer recorded by "queue" in time order?

    Hi Paul, Got it! Thank you for your fast response!!
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    Are the 128 samples in one buffer recorded by "queue" in time order?

    Hi everyone, A quick and simple question: I was wondering if the 128 samples in each buffer recorded by "queue" are in time order? I'm trying to connect these samples from all buffers, so that I could obtain continuous time data over a certain period of time. I assume they are in time order...
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    Audio lineIn reading data from SDplay output without any connections

    Hi, SteveMcl! I'm doing a similar project just like yours, and got the same issue. Here's the link to my thread: Unexpected FFT Peak with Disconnected Sensors. I'm using "waveform" to generate a 10khz signal on line_out, and saving data recorded from line_in. Then, plot their FFTs. The problem...
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    Unexpected FFT Peak with Disconnected Sensors

    Hi mjs513, thank you so much for your help! I followed your instruction and commented out "sgtl5000_1.volume(1);". But still I could see the peak at 10kHz when disconnected line_in and line_out. Here are the two FFTs in linear scale and logarithmic scale. Is that the same result you got? Seems...
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    Unexpected FFT Peak with Disconnected Sensors

    Thanks for your reply! Yes, if you delete the "waveform" and "waveform.begin", it works only as a receiver, which works well. But here I tend to make the receiver and speaker work simultaneously. Still don't know how to do that. Thank you!!
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    Unexpected FFT Peak with Disconnected Sensors

    Thank you for your reply! I tried your sketch, but sometimes I would have errors recording data, then I can't plot FFT. I think the reason might be "delayMicroseconds(50)", so what is the purpose for using this here? But those errors only occurred occasionally, sometimes I could plot the FFT...
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    Unexpected FFT Peak with Disconnected Sensors

    Hi. Thanks for your reply! Yes, I'm attaching "waveform" to the output, so the speaker(emitter) could keep generating signals. Do you mean the "line_in" could always capture the signals(waves) I attached on "line_out", even when nothing is connected to "line_in" & "line_out"? So the...
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    Unexpected FFT Peak with Disconnected Sensors

    Sorry for the confusion! Here are my current setup where "line_out" is connected to the speaker(emitter) and "line_in" is connected to the receiver. I used the same type of sensors for this, which is a piezoelectric sensor. They are just directly connected to the "line_in" and "line_out". And I...
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    Unexpected FFT Peak with Disconnected Sensors

    This is exactly what I'm doing here. I want the speaker (emitter) and receiver work simultaneously. So, the "waveform" here is what I used to generate a signal on Line_Out. I could set the frequency to any value, and still we could see the peak at the value I set. For example, if I set it to...
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    Unexpected FFT Peak with Disconnected Sensors

    Good idea! Here's what the logarithmic spectrogram looks like. There's still a dominant peak at 10kHz, when nothing is connected.
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    Unexpected FFT Peak with Disconnected Sensors

    Yes, the level here is exact 5e8 which is really high! When sensors are connected, the level of the peak lies from 2e8 to 5e8 while I set the frequency (of the emitter) from 20Hz to 20kHz. So, if sensors are disconnected, there is still a dominant peak (5e8).
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    Unexpected FFT Peak with Disconnected Sensors

    Sorry guys! Here are the attached python files, they can only be attached in txt format. One is for saving data ("read_serial") and the other is for plotting FFT ("plot_fft").
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    Unexpected FFT Peak with Disconnected Sensors

    Hi everyone, I'm doing an audio project on Teensy 4.0 integrating with Audio Shield. Two sensors are connected on the Audio Shield with one emitting signals and the other receiving them. For the emitter, I use "waveform" from audio lib to generate signal at a specific frequency, and I use...
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