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  1. Replies
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    Then just the analog ground pins of the...

    Then just the analog ground pins of the linein/lineout connection pads. You don't want a ground loop,
    you don't want digital hash coming in from the digital ground.
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    Each signal should have a ground return running...

    Each signal should have a ground return running alongside it at logic speeds. Logic edges are "damn fast", you risk
    crosstalk and other issues without good layout. I'd suggest 1 ground wire for...
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    receive and output what? analog or digital (or...

    receive and output what? analog or digital (or both)?
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    The SGTL is 0.5mm pitch TFN - no point risking...

    The SGTL is 0.5mm pitch TFN - no point risking hand soldering on that. This really requires either an oven or a hot-air rework station,
    and you'll need to use solder paste and a stencil (and a...
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    No ground returns on the ribbon? Not a good...

    No ground returns on the ribbon? Not a good idea, you have two ground pins you can use for this.
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    Check every pointer for NULL - you don't check...

    Check every pointer for NULL - you don't check the result of pop_front() for instance.

    Some of your functions do checking after allocating resources, then have to return the resources unused if...
  7. Wouldn't that just need stacking headers for the...

    Wouldn't that just need stacking headers for the Teensy?
  8. I think the problem is connecting the analog pin...

    I think the problem is connecting the analog pin to the whole typewriter frame - this will pick up a lot of noise due to
    its large capacitance to the surroundings (ie pick up loads of mains hum).
    ...
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    It wouldn't be ethernet compliant of course, but...

    It wouldn't be ethernet compliant of course, but I suspect for short cable runs you could get away with it, until someone plugs the cable into a PoE sender that is.
  10. The 4051 is an analog multiplexer, not a shift...

    The 4051 is an analog multiplexer, not a shift register, meaning it can route signals agnostic of whether they are
    inputs or outputs. No shifting happens.
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    Sugru is listed as having a thermal conductivity...

    Sugru is listed as having a thermal conductivity of only 0.189 W/m/K, which might be an issue.
    Thermal potting compounds are available with much higher conductivity.

    Also I found:...
  12. I know 87kHz is used for cave rescue services in...

    I know 87kHz is used for cave rescue services in the UK, its probably licensed for single-sideband only - many "public use"
    bands have bandplans that prescribe the modulation types, duty cycles and...
  13. HTTP requires "\r\n" as a line ending for every...

    HTTP requires "\r\n" as a line ending for every header line and for the mandatory blank line before the content body.

    So change lines like:


    client.println("POST...
  14. https://github.com/PaulStoffregen/Audio/pull/400...

    https://github.com/PaulStoffregen/Audio/pull/400

    Not sure about shortnames - it currently uses the id I think which has the Audio class name embedded in it, or similar.
  15. Forgot to declare pullups? I don't think you...

    Forgot to declare pullups?

    I don't think you mean noise - be aware of the difference between noise, interference and signal - here you have a signal
    you want to sense I think - but its unclear
    ...
  16. Can you fix the malformed code and use code tags...

    Can you fix the malformed code and use code tags please - no easy way to copy/paste that....
  17. This is because the matching is case sensitive...

    This is because the matching is case sensitive and you didn't type "Delay" - not a great user experience...

    Line 152 in gui/red/ui/palette.js needs to be changed from


    var re = new...
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    Well the diurnal variation can be 20C in...

    Well the diurnal variation can be 20C in temperate areas and 60C in a desert,
    and a summer thunderstorm is a large and rapid cooling event in a metal enclosure.
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    Chipset heatsinks typically come with suitable...

    Chipset heatsinks typically come with suitable adhesive already - I measure on a T4.0 that there's a 20mmx12mm area clear of obstructions,
    can probably cut down a chipset heatsink for that.
    ...
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    The official library is 16 bit throughout, though...

    The official library is 16 bit throughout, though some people are working on branches that extend to higher bitdepth -
    have a search around, theres a few active threads on these IIRC.

    The...
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    That gave me a shock till I realized you mean...

    That gave me a shock till I realized you mean Farenheit. Electronics uses degrees C, read any datasheet.
    75 degrees C doesn't sound too bad. I mean you'd like it to run cooler if possible, but...
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    You don't have to provide the maximum rated...

    You don't have to provide the maximum rated current to an LED - in fact today they are so efficient that
    this is usually blindingly bright.

    Try 1mA to 5mA range - some experimentation may be...
  23. It strikes me a LA with dual comparator sets...

    It strikes me a LA with dual comparator sets would be able to show trapezoidal waveforms fairly accurately and indicate fault
    conditions (static and dynamic discipline violations). Just having a...
  24. Yes, that's the issue I think, with 100MHz...

    Yes, that's the issue I think, with 100MHz bandwidth you'll see
    25322
    for SCLK at 5MHz

    That LA's analog mode uses much slower ADC that has 12 bit resolution - the digital channels are fast but 1...
  25. Looks like you are using the analog inputs (BW...

    Looks like you are using the analog inputs (BW 5MHz), rather than digital inputs for this.
  26. If you want to generate very high frequency PWM...

    If you want to generate very high frequency PWM perhaps?

    I've used limited resolution PWM at high speed to allow noise-shaping for instance. The noise
    shaping has the side effect of increasing...
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    Some but not all audio objects can use a...

    Some but not all audio objects can use a different power-of-two for the samples per block - I know the FFT
    objects assume 128, but many are agnostic. I would risk lower than 8 though and often the...
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    This will be capacitive coupling issues I think -...

    This will be capacitive coupling issues I think - ADC input sample/hold caps on modern silicon are only a few pF.
    If you want noise-free ADC operation you may have to stop the processor to eliminate...
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    Here's a crazy(?) thought: Low temperature...

    Here's a crazy(?) thought: Low temperature solder paste squeegeed on the holes for the pins, oven reflow... Header
    pins are unlikely to see any high temperatures, and a low temperature oven cycle...
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    Only one variable is needed: uint32_t...

    Only one variable is needed:


    uint32_t count = 0 ;
    count -= ARM_DWT_CYCCNT;
    ... code to time ...
    count += ARM_DWT_CYCCNT;

    Using the -= allows discontinuous time periods to be summed...
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    C#? Garbage collection overhead perhaps?

    C#? Garbage collection overhead perhaps?
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    You simply record 10 values per second, being the...

    You simply record 10 values per second, being the counts at 0.0s, 0.1s, 0.2s etc, and when a new value comes in take
    the difference from the one 1.0s ago. Display can update every 0.1s, the counts...
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    The resistor needs to be small enough to prevent...

    The resistor needs to be small enough to prevent the output straying from the compliance range, which is typically less than a diode drop.
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    UDP is best thought of as Unreliable Datagram...

    UDP is best thought of as Unreliable Datagram Protocol, even though it stands for User Datagram Protocol!

    Reordering, packet loss, packet duplication, all can happen with UDP. Its not intended...
  35. Thread: Teensy 4.0

    by MarkT
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    That chip seems to support I2C fast mode - are...

    That chip seems to support I2C fast mode - are you already using this?
  36. https://www.pjrc.com/store/header_14x1_d.html...

    https://www.pjrc.com/store/header_14x1_d.html
    Are recommended, but standard male to female headers leave plenty of room and allow access and stacking with other
    boards if you need to.
  37. Clearance between the boards?

    Clearance between the boards?
  38. Replies
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    Actually people don't really hear jitter, they...

    Actually people don't really hear jitter, they hear the spurious tones due to jitter corrupting the spectrum - jitter
    causes intermodulation with the signal tones, and if the intermodulation...
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    Instability is one possibility as I stated, the...

    Instability is one possibility as I stated, the headphone ground output is not meant to be loaded w.r.t. real ground, it seems it might be
    the output from an internal opamp on the chip AFAICT, which...
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    The output of the filter should be float or at...

    The output of the filter should be float or at least fixed point, not integer, the correct solution to your problem is to
    add hysteresis to your thresholding I think. The steady state ought to be...
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    Its a fundamental trade-off - the bandlimited...

    Its a fundamental trade-off - the bandlimited waveforms use table-driven sinc-interpolation, which is the fastest way
    I could find to implement a good quality interpolation (all spurs well down to...
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    Not sure its possible to miss the design tool: ...

    Not sure its possible to miss the design tool:

    https://www.pjrc.com/teensy/gui/
    click on to each object on the left to see its docs.
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    There's a whole slew of docs for the audio...

    There's a whole slew of docs for the audio library, and a video, and it comes with lots of examples.
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    Sounds entirely as expected - ISRs taking a...

    Sounds entirely as expected - ISRs taking a couple of microseconds aren't normally a problem, and 70ns jitter on a machine with a
    complex CPU with caching isn't a surprize, cache-misses are...
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    I still don't see what you are trying to do: ...

    I still don't see what you are trying to do:

    Is 61 nearer to 60 than to 62? Its fundamentally ambiguous. Perhaps you didn't mean "nearest"?
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    Do you mean vibrato (pitch modulation) or tremolo...

    Do you mean vibrato (pitch modulation) or tremolo (volume modulation)?
    Yes its easy to generate low frequency modulation signals with the various oscillator (waveform) classes.
    There is the...
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    Since MIDI notes are semitones and most scales...

    Since MIDI notes are semitones and most scales have whole tone intervals this is ambiguous:
    do you sharpen a rogue note or flatten it? Only with intervals of 3 semitones or more can "closest...
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    For instance searching for I18N should find...

    For instance searching for I18N should find things like gettext: https://en.wikipedia.org/wiki/Gettext
  49. You said you were memory limited, this is one way...

    You said you were memory limited, this is one way of trading speed for space.
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    A common technique is to use code numbers for...

    A common technique is to use code numbers for text strings, and a dynamic mapping occurs when printing strings to
    the screen, dependent on the selected language. I'd suggest googling "I18N"
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