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  1. Replies
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    Erm, that's how the chip is wired - both paths...

    Erm, that's how the chip is wired - both paths use the same switched attenuator. You cannot have both mic and line-in at once
    since there's only one ADC, the attenuator is for the ADC. Mic input...
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    micGain() and lineInLevel() both control it via...

    micGain() and lineInLevel() both control it via the CHIP_ANA_ADC_CTRL register. The micGain() method also sets the coarse mic gain.

    Source in...
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    Anything that waits for (lower priority)...

    Anything that waits for (lower priority) interrupts can be an issue, but more generally avoid anything
    that takes a lot of time or may block (ie does busy-waiting for anything that's not guaranteed...
  4. I presume the serial pin has pullups enabled as...

    I presume the serial pin has pullups enabled as high is the idle state for TTL serial lines. Try turning off the pull up
    for hibernation. The powered down sensor will pull the pin low while its...
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    integer variables in C are modular, so you need...

    integer variables in C are modular, so you need to do the subtraction modulo the relevant power of two. For instance with uint32_t:


    millis start millis-start
    0xFFFFFFF0 0xFFFFFFF0 ...
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    Complete aside: your MyDelay isn't safe from...

    Complete aside:
    your MyDelay isn't safe from wraparound, code it like this:


    void MyDelay(unsigned long WaitTime){
    unsigned long StartTime = millis();
    while (millis() - StartTime <...
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    Indeed, and if you use this you'd implement the...

    Indeed, and if you use this you'd implement the various filter sections using the AudioFilterBiquad class,
    but first you have to generate the filter coefficients - the original code just uses...
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    IPA is not the alcohol it is designed for, it is...

    IPA is not the alcohol it is designed for, it is for ethanol, not isopropanol - the clue really is in the name!!

    Reading a bit more it seems these sensors actually measure permittivity so its...
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    I was thinking save the output to the SDcard...

    I was thinking save the output to the SDcard too... If that works
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    Apparently there are counterfeits of this sensor...

    Apparently there are counterfeits of this sensor around. Do you have an indepedent means to check the output frequency
    such as a 'scope (some multimeters can do frequency too)?

    I believe its 5V...
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    The typical current draw of the screen is stated...

    The typical current draw of the screen is stated as 9mA. So the 2k2 resistor can't really be powering the display, its probably
    being phantom-powered via the I2C pins which is not a good idea at...
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    You mentioned Matlab before - surely it can...

    You mentioned Matlab before - surely it can generate whatever you want?
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    No, the latency is a fixed number of blocks, this...

    No, the latency is a fixed number of blocks, this is just like a pipeline.
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    I've had a quick scan of the code, and I think...

    I've had a quick scan of the code, and I think you need to use two blocks per FFT, so that the overlap
    is 50% of the FFT period - the current code seems to have no overlap.

    BTW a Hann window...
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    A wide-range bandpass filter is easiest to...

    A wide-range bandpass filter is easiest to realize as a high-pass filter and a low-pass filter chained together.
    Can you generate Butterworth low-pass and high-pass filters? There are many on-line...
  16. Sounds travels much faster in solids than air, so...

    Sounds travels much faster in solids than air, so you may have multiple paths for acoustic energy to travel to your sensors unless
    you go for the shortest path inside the solid target itself? In...
  17. That's what I mean - in software you can...

    That's what I mean - in software you can crossfade instantly as well as gradually.
  18. Thread: Measure mV

    by MarkT
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    You need to shift the signal to mid-way between...

    You need to shift the signal to mid-way between the voltage rails. The negative voltages cannot be measured by the ADC,
    and if more than 0.3V or so could damage the chip permanently.

    Normally a...
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    I'd advise always disabling file-hiding in any OS...

    I'd advise always disabling file-hiding in any OS you use, otherwise it will bite you one day.
  20. IC2 is used as a 4-bit address comparator I think...

    IC2 is used as a 4-bit address comparator I think - and is set by the (jumpers?) you've labelled CON. 2
    Until that matches the 245 won't drive anything - is that what writeBoardAddress(3) is...
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    Well as the MOSFET is logic level I'd expect it...

    Well as the MOSFET is logic level I'd expect it to work at any of those voltages no problem.
    I'd suggest careful checking of your circuit, especially the OUTL connection.

    Note the 100nF cap on...
  22. Like all CMOS chips a pair of Schottky diodes to...

    Like all CMOS chips a pair of Schottky diodes to the rails and a series resistor will do the job of protecting inputs.
    To my knowledge exceeding the rails in the inputs by more than a diode drop...
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    You haven't indicated any Vcc in the diagram so...

    You haven't indicated any Vcc in the diagram so its not at all clear what you mean.
  24. You seem to be turning wav file volume on at the...

    You seem to be turning wav file volume on at the same time as microphone volome on, rather than cross-fading -
    I thought you wanted to cross-fade between them?
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    That chip is limited to 10MHz SPI, you need to...

    That chip is limited to 10MHz SPI, you need to ensure the Teensy version sets the SPI clock speed to <= 10MHz.
    The Uno is physically imcapable of clocking faster than 8MHz so it won't see this...
  26. Which module? Is it I2S master or slave?

    Which module? Is it I2S master or slave?
  27. But only in the abbreviated form... Hz stands...

    But only in the abbreviated form... Hz stands for hertz, N for newton, A for ampere. This distinquishes the unit from
    the person (as in "the newton (N) is named after Newton").

    There is one...
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    Grounding the input means connecting it to ground...

    Grounding the input means connecting it to ground (0V normally). Gnd is short for ground
  29. Add an AudioInputI2S and connect it to channels 2...

    Add an AudioInputI2S and connect it to channels 2 on both mixer1 and mixer2.

    Initialize the sgtl5000 to use microphone input and configure the mic gain as necessary. By turning the channel 2...
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    The outputs are not designed to be continuously...

    The outputs are not designed to be continuously shorted even in current limited modes, so always use a resistor with an LED.
    The configuration of output currents is about reducing EMI, not driving...
  31. Forum rule is there for a reason... Post your...

    Forum rule is there for a reason... Post your current code and explain what's not working?
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    Well I think its various lines of code, the setup...

    Well I think its various lines of code, the setup for I2S hardware could be copied from the I2S classes and the BCLK changed to
    16 per sample from the 32 per sample used by the audio library. What...
  33. Uses half as much memory and nearly twice as fast...

    Uses half as much memory and nearly twice as fast I suspect. An N-point FFT with real inputs can be done using an N/2-point complex FFT
    using some clever pre- and post-processing.

    An N-point...
  34. It has various logic to set the mode variable,...

    It has various logic to set the mode variable, and then updates various mixer gains dependent on the mode.
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    An audio device with nothing plugged in is going...

    An audio device with nothing plugged in is going to see the thermal noise from its internal load resistance, which can be considerable if this is
    the standard value (50k). With a low-impedance...
  36. The internal clock speed of a processor is often...

    The internal clock speed of a processor is often higher than the speed the GPIO pads are clocked, since those aren't in the
    low voltage core of the chip which has the fastest speed. This is why...
  37. OK its not line endings then, but taking another...

    OK its not line endings then, but taking another look this is a worry:


    client.println("Host: https://eu-central-1-1.aws.cloud2.influxdata.com");

    Since the Host line takes a domain and port...
  38. Yes, you use a mixer to combine them as I said. ...

    Yes, you use a mixer to combine them as I said. You can choose whatever combination you like - the mixer is just an audio mixer with
    control inputs from 0 to 1 representing the range of movement in...
  39. Perhaps that's not generating valid HTTP headers....

    Perhaps that's not generating valid HTTP headers. Every line in an HTTP header _must_ end with \r\n, including the blank line at the end of the headers.
    I don't know if the EthernetClient library...
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    Could it just be clipping that you are...

    Could it just be clipping that you are experiencing? The Audio shield inputs have a limited voltage range they can tolerate
    (somewhat less than 3.3V peak-2-peak) before they clip, and once above...
  41. Its a decoupling capacitor so the value isn't...

    Its a decoupling capacitor so the value isn't critical. The polarized symbol on the schematics is a known inaccuracy, they are all MLCC's (there isn't room for anything else)
  42. Perhaps use a mixer with the mic input and synth...

    Perhaps use a mixer with the mic input and synth waveforms as inputs, allowing switching/crossfading between these sources?
  43. Just feed an attenuated sample of the TX coil to...

    Just feed an attenuated sample of the TX coil to the other channel and you can compare the phases between channels perhaps?
  44. Since the system samples at 44100Hz, 22kHz is...

    Since the system samples at 44100Hz, 22kHz is indeed the maximum frequency supported by the Audio library, in its out-of-the-box configuration. Increasing this is possible, there are various threads...
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    The AudioOutputI2S2slave class is work in...

    The AudioOutputI2S2slave class is work in progress I think - its commented out in the sources at the moment.

    The classes are named from the Teensy's point of view - ie the slave classes work with...
  46. I guess that's perfectly possible - you'd need to...

    I guess that's perfectly possible - you'd need to ensure suitable scaling of the received signal to the right level for best sensitivity without clipping too readily.
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    Or I think you can use AudioOutputI2S and...

    Or I think you can use AudioOutputI2S and AudioOutputI2S2 together if on an Teensy 4.x
  48. Pretty sure it doesn't from what I've seen here...

    Pretty sure it doesn't from what I've seen here (not played with it myself)
    USB doesn't run on a 44.1kHz clock, so I presume it can't do the timing for the library like the I2S hardware.

    If you...
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    FYI: surface mount resistors are identifiable as...

    FYI: surface mount resistors are identifiable as they are nearly always black on top with white printing on them
    showing the value (unless really tiny) they also have metal endcaps.

    Brown/tan...
  50. You need at least one class that generates...

    You need at least one class that generates regular interrupts to fire up the whole audio library - try adding one of
    the I2S classes. I suspect the mono and stereo analog inputs differ in this.
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