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  1. Replies
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    I've stared at the code again and think I've...

    I've stared at the code again and think I've found a bug to do with this:



    void AudioFilterBiquad::setCoefficients(uint32_t stage, const int *coefficients)
    {
    if (stage >= 4) return;...
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    gfft? Is this just the FFT's or including...

    gfft?

    Is this just the FFT's or including screen updates?
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    3W, not 4W, so 1.75W in the regulator, but as I...

    3W, not 4W, so 1.75W in the regulator, but as I say still far too much without good thermal design (heatsinking).
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    Yes, its pullups for I2C:...

    Yes, its pullups for I2C: https://en.wikipedia.org/wiki/I%C2%B2C#Physical_layer

    However if you are 3.3V driving 5.0V the pullups might be an issue with the protection diodes
    in the Teensy driving...
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    Using differential signalling is going to...

    Using differential signalling is going to maximize your change of success for this, so lets hope it works first time!
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    I just picked one of the examples - have you...

    I just picked one of the examples - have you checked if they compile (and copied how they set things up)?
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    You appear to have a DPak or DPak2 linear...

    You appear to have a DPak or DPak2 linear regulator without any thermal plane? The T4 can easily take 0.25A at full speed,
    plus you have other circuitry, so lets estimate 0.3A, so dropping from...
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    You need to include at least one audio object...

    You need to include at least one audio object that generates a clock, for instance AudioInputI2S or AudioOutputI2S.
    Without a clocked object nothing ever happens.
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    I think we're at cross-purposes, I'm talking...

    I think we're at cross-purposes, I'm talking about methods of generating sampled sinusoids that are way faster than sincosf,
    3 add/subs and 2 muls to generate both sin and cos per sample. Its the...
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    I have some code using one of the techniques for...

    I have some code using one of the techniques for generating sines (in fact this one generates quadrature,
    ie cosine and sine simultaneously), in one of my experiment branches of the Audio library:...
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    I see these errors: ...

    I see these errors:



    /Users/markt/teensy_sketchbook/libraries/RMCS2303drive/src/RMCS2303drive.cpp:25:19: error: comparison between distinct pointer types 'HardwareSerial*' and...
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    Great, but note that I just skimmed the datasheet...

    Great, but note that I just skimmed the datasheet for the pinout and the application circuit - always worth doing.
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    It will work fine with only 16 bits, I2S is...

    It will work fine with only 16 bits, I2S is designed to be smart about this.

    There are several ways to sythesize sine waves efficiently, table lookup is not the only way as there are several...
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    From my reading of the code yes, but why not...

    From my reading of the code yes, but why not actually try it to be sure?
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    In general using a delay style function will be...

    In general using a delay style function will be inaccurate as it only accounts for time in the delay call,
    not time outside it. If there were a nanos() call (which could be useful for the T4 ...)...
  16. "The CPU values are in percent" means the units...

    "The CPU values are in percent" means the units are percent. So 0.59 means 0.59%, or as a fraction 0.0059 of the time.

    2,4 means 2 blocks live last time, 4 blocks live being the maximum ever...
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    Just do biquad.setBandpass(0,1000,1); ...

    Just do

    biquad.setBandpass(0,1000,1);

    again. Each stage definition will terminate the string of filter stages unless it is for a stage one more than the last one,
    so redefining the first...
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    I'd suggest starting with a good tutorial on...

    I'd suggest starting with a good tutorial on state machines, this is rather lengthy but looks to be a good guide:
    https://barrgroup.com/Embedded-Systems/How-To/State-Machines-Event-Driven-Systems
    ...
  19. The CPU values are percent, so if there was an...

    The CPU values are percent, so if there was an overload it would have to be in the low-level
    DMA interrupt(s). From the low and constant value is suggests no processing is done in
    the Audio...
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    I'm pretty sure I can see a solder short in the...

    I'm pretty sure I can see a solder short in the third image, one of the top pin row has a little blip
    of solder over the horizontal bus trace?
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    Figure out the states you need to represent this,...

    Figure out the states you need to represent this, I think you probably need:

    IDLE
    PRESSED
    PRESSED_LONG

    Use a variable to explicitly record the current state so you can respond to the...
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    I think the 4mA is the max nominal output drive...

    I think the 4mA is the max nominal output drive current setting for a pin - not the abs max current you can actually draw - I can't
    remember seeing that in the datasheet when I was looking.
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    The issue I see from the videos seems to involve...

    The issue I see from the videos seems to involve speckling and artifacts that might be to do with
    the colour mapping, doesn't seem to be just shape issues. It also might not be resampling suitable...
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    Forum rule?

    Forum rule?
  25. Each interrupt can capture the timestamp when it...

    Each interrupt can capture the timestamp when it fires, the main code can wait for these to change and take the
    difference perhaps?
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    can you be specific as to what is happening?...

    can you be specific as to what is happening?
    Pics perhaps?

    Forum rule?
  27. Replies
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    I think this page is what you want for separate...

    I think this page is what you want for separate powering:
    https://www.pjrc.com/teensy/external_power.html

    if everything's 5V and not needing lots of current this is usually simple, use one...
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    The ATmega32u4 datasheet says absolute maximum...

    The ATmega32u4 datasheet says absolute maximum 40mA per pin.

    But input pins take no current(*), provided the voltage is within the supply rails, which it should be
    if the switch / pot in question...
  29. Use whatever Vcc you have. Most people wouldn't...

    Use whatever Vcc you have. Most people wouldn't bother and just use internal pullups - it that's unreliable there
    might be some benefit from small caps. (Note the issue is not normally a problem...
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    Perhaps the alignment optical feedback system...

    Perhaps the alignment optical feedback system isn't programmed for the connector, or there are reflection/glare
    issues - good pick-and-place machines finalize the orientation and position using a...
  31. Have you used...

    Have you used AudioProcessorUsage/AudioProcessorUsageMax/AudioMemoryUsage/AudioMemoryUsageMax?
    Always worth chucking this in when experimenting:



    void loop ()
    {
    static unsigned long...
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    actually yes I believe so - arm_q15_to_flt...

    actually yes I believe so - arm_q15_to_flt perhaps? Something like that.

    I was assuming so given the use of floats...
  33. It would indeed be feasible for the envelope -...

    It would indeed be feasible for the envelope - the "mult_hires" variable in AudioEffectEnvelope is a fixed point 2.30
    value you could sample with an extra method.

    For the waveform itself the...
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    Dividing by a constant is likely slower than...

    Dividing by a constant is likely slower than multiplying by the reciprocal -


    const float recip = 1.0f/INT16_MAX ;

    ...
    blockFloat[i] = blocka->data[i] * recip;

    I'm not sure if the...
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    Some plastic film are stacked, some are wound,...

    Some plastic film are stacked, some are wound, and some wound types can be much more inductive and
    not likely to be much use for high speed decoupling.

    Standard practice is MLCC for high speed...
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    14 bit resolution for CC is perfectly possible -...

    14 bit resolution for CC is perfectly possible - it takes more bytes on the wire of course which can be an issue,
    and the MIDI sender has to know to use the 14 bit extensions for the controls in...
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    I suspect the residual noise from slewing is...

    I suspect the residual noise from slewing is because its only a 1st-order correction to the previously discontinuous gain
    changes - the derivative of the gain still has discontinuities at the start...
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    Forum rule?

    Forum rule?
  39. Some metal components are actually available with...

    Some metal components are actually available with kapton tape pre-fitted - its the industry-standard way to fix this kind of issue ;)
  40. 345Hz is the rate of audio blocks in the audio...

    345Hz is the rate of audio blocks in the audio lib, could that "320Hz" actually be 345Hz?
    If so I suspect some problem like insufficient AudioMemory - certainly posting your code would
    allow...
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    You'll need the audio lib to run at 96kSPS from...

    You'll need the audio lib to run at 96kSPS from what you say, and have a bespoke version of AudioOutputUSB
    that decimates its input by 2 to drive out at 48kSPS

    Or just use 96kSPS throughout, I...
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    Do you have a hot-air rework station? Without...

    Do you have a hot-air rework station? Without that it may be difficult to successfully reattach to the PCB - and
    even so you'd need to be very careful about temperature as these plastic parts will...
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    Are you changing AUDIO_BLOCK_SAMPLES? Presumably...

    Are you changing AUDIO_BLOCK_SAMPLES? Presumably you've set AUDIO_SAMPLE_RATE_EXACT to 48000.0 ?
    Are you expecting to run the Audio lib at 96 or 48kSPS?
    Do you want good anti-aliasing performance...
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    That's a distortion effect, not a compression...

    That's a distortion effect, not a compression effect. To compress you need to use a linear response whose gain
    varies over time at scales longer than 50ms. (possibly several independent sections...
  45. True but the page refers you to a double...

    True but the page refers you to a double insulator spaced 14 pin strip designed specifically to provide
    good spacing: https://www.pjrc.com/store/header_14x1_d.html
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    Some quadrature encoders have sin/cos analog...

    Some quadrature encoders have sin/cos analog output between the digital counts for much finer
    precision and smoother velocity sensing.
  47. Those dupont male header strips are designed to...

    Those dupont male header strips are designed to be used with female dupont headers and that provides 1/2" clearance.
    It seems you've just used the male headers as permanent board-to-board connector.
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    My thoughts: no fuse on the +ve from the battery...

    My thoughts: no fuse on the +ve from the battery is bad news - these batteries can source vast currents on a fault condition.

    You try to power a boost converter (which contains an inductor) from...
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    AC millivolt settings on a multimeter may be...

    AC millivolt settings on a multimeter may be severely band-limiting to a few 100 Hz or low kHz - AC on a multimeter
    is designed for mains, definitely not for measuring broadband noise.

    Noise...
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    Another approach to reducing this zipper noise...

    Another approach to reducing this zipper noise (as its called - its also happens in hardware if you
    use digital potentiometer chips) is to do zero-crossing synchronization - any pending gain change...
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