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  1. Replies
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    They are really just FETs with long thin...

    They are really just FETs with long thin channels, rather than resistors proper, so the process variation is large.
    True on chip resistors would be probably 100's of times the silicon real-estate...
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    WM8731? Not seen that - all the Teensy audio...

    WM8731? Not seen that - all the Teensy audio adapter versions use the SGTL5000 AFAICT.
  3. In short I'd divide the processor landscape like...

    In short I'd divide the processor landscape like this:

    Microcontrollers have many interfaces to drive sensors and things like motor drivers. They do not need
    support chips to function. Typical...
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    The AudioSynthWaveform only does random sample...

    The AudioSynthWaveform only does random sample and hold. It doesn't take an input.

    The AudioEffectBitcrusher class has a sampleRate() method which might be more what you want.
  5. In C and C++ pointers and arrays are basically...

    In C and C++ pointers and arrays are basically interchangable, different views on the same memory model, so you'd
    never expect a difference in performance whatever processor.

    You can't pass...
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    Yes that makes perfect sense, internal pullups...

    Yes that makes perfect sense, internal pullups are often too weak for off-board signals (or even on-board signals
    if the layout is unfavorable) - use 10k physical pullup in the first instance,...
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    Note that logic input signals have a _minimum_...

    Note that logic input signals have a _minimum_ slew-rate specification, typically for a fast CMOS chip it might be over 100V/s.
    The T4.x chip requires logic transitions to be 25ns or faster when a...
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    I'd hope those voltages are a symptom of a flat...

    I'd hope those voltages are a symptom of a flat battery in the multimeter, not the actual voltages on the Teensy...
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    150mA stepper motor current level, which needs...

    150mA stepper motor current level, which needs programming into the stepper driver module
    as per instructions for that stepper driver module.
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    That'll be 150mA, 55 ohm then, which will need at...

    That'll be 150mA, 55 ohm then, which will need at least 12V for the A4988 to drive properly, and would benefit from
    higher voltage to overcome the winding impedance better (this is mainly...
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    You have connected to the right pads? There are...

    You have connected to the right pads? There are both line output and line input pads on the Audio adapter. I suppose
    this must be right for the rms meter to work.

    You are inputing line level...
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    Q2 has nothing to limit the base current, so...

    Q2 has nothing to limit the base current, so it'll be immediate toast if the ATTREQ line is driven to 5V. Perhaps 10k
    base resistor will fix that.

    The ATTNREQ line has a series resistor, and is...
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    55 ohms is quite large - nothing like the motor...

    55 ohms is quite large - nothing like the motor you link to as "rather similar".
    What size is the motor - this will be a more reliable guide to its dissipation limit, and thus figuring
    out a likely...
  14. The AudioSynthWaveformModulated only supports a...

    The AudioSynthWaveformModulated only supports a single modulation stream so can only do one
    of FM or PM at one time.

    You'd have to write a more general version with two modulation streams in to...
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    AudioConnection patchCord1(audioInput, 0, myFFT,...

    AudioConnection patchCord1(audioInput, 0, myFFT, 0);


    That only looks at the left channel - perhaps you only have the right channel with a signal?

    BTW Code tags (the # button) are used for...
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    With a multimeter in ohms setting you can...

    With a multimeter in ohms setting you can identify the two separate windings of the stepper, what's important
    is that one winding goes to 1A/1B and the other to 2A/2B on that module - alas the...
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    Can you post the code that shows the problem?

    Can you post the code that shows the problem?
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    That sounds very like the title of a whitepaper...

    That sounds very like the title of a whitepaper from analog devices or similar, let me search:
    Ah, not quite, I think this might be what I was remembering: ...
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    You have the source code within the Teensyduino...

    You have the source code within the Teensyduino app, though precisely where the files live
    depends on OS. I simply grep the source tree locally to find stuff. There are many similar
    code search...
  20. In the first picture I don't think I can see the...

    In the first picture I don't think I can see the ground-return for the PWM signal to the ESC - ideally
    this would be on the same shielded cable, or twisted pair, to reduce EMI pickup on the...
  21. Which Teensy? i.e. what voltage is the PWM? For...

    Which Teensy? i.e. what voltage is the PWM? For instance is the ESC 5V and the Teensy 3.3V?

    I suspect there will be some heavy interference involved due to the high currents involved - cable...
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    That's basically measuring the SINAD directly for...

    That's basically measuring the SINAD directly for a sinusoid.
  23. Thread: lfo phase reset

    by MarkT
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    The phase() call changes the phase of the...

    The phase() call changes the phase of the waveform relative to the original phase, allowing phase modulation
    in steps, for instance. It doesn't change the original phase which is set at the time...
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    The quantization noise is about 98dB below max...

    The quantization noise is about 98dB below max signal power for 16 bits (for a square wave, or 95dB for a sinusoid).
    This is the noise power, not the noise's PSD (power spectral density, which is...
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    There is the classic Boyer-Moore algorithm:...

    There is the classic Boyer-Moore algorithm: https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string-search_algorithm
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    Firstly there's no need for interrupts for...

    Firstly there's no need for interrupts for something this slow (from the Teensy 4's perspective :)). You have two
    tasks, counting incoming pulses and generating outgoing pulses - the delay you use...
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    Do you mean PWM pins? Each H-bridge on the chip...

    Do you mean PWM pins?
    Each H-bridge on the chip takes a direction (which they misleadingly call phase) and enable digital logic signals. You would
    typically PWM only one of those pins, depending...
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    I built an adapter using stacking headers and...

    I built an adapter using stacking headers and stripboard to solve this problem for my T4.0 - in retrospect I
    should have populated either the Audio adapter or Teensy itself with stacking headers....
  29. Can the audio block release() method not deal gracefully with NULL pointers?

    Currently there is a commented out piece of code at the start of release()
    that I feel would be useful to uncomment:

    // Release ownership of a data block. If no
    // other streams have ownership,...
  30. Thread: Benchmark

    by MarkT
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    I guess a benchmark suite, rather than just one...

    I guess a benchmark suite, rather than just one benchmark program, so that different styles of coding are
    covered such as integer, floating point, DSP, decision logic, function-call intensive,...
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    What spectrum do you get for a 1kHz tone?

    What spectrum do you get for a 1kHz tone?
  32. I note one of my old Arduino boards has two 47F...

    I note one of my old Arduino boards has two 47F caps, but the current USB2 specifications say 10uF max...
  33. You can use serial, the Arduino Mega has 4 serial...

    You can use serial, the Arduino Mega has 4 serial interfaces. You'll need a level converter for each direction, but at a
    pinch you can use a resistive divider 1k:2k2 for 5v->3.3V and just directly...
  34. Stretching by which ratio or ratios?

    Stretching by which ratio or ratios?
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    The Audio adapter board has DC-blocking...

    The Audio adapter board has DC-blocking capacitors on the line inputs and line outputs. Any audio device will handle proper AC
    correctly (and some do not like a DC bias at all, for instance a...
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    AudioMemory(12); BTW there are only 12 blocks...

    AudioMemory(12);

    BTW there are only 12 blocks available to any audio class due to this call.
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    No, the processor is 3.3V however you...

    No, the processor is 3.3V however you power/modify the board.
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    0.35W * 200C/W + 25C = 95C. Temperature rise...

    0.35W * 200C/W + 25C = 95C. Temperature rise above ambient. Ideally keep components below 50C for a long reliable life and
    avoid burning yourself too(!)
    If you start pulling current from the...
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    Nothing obviously wrong with the code to my eyes....

    Nothing obviously wrong with the code to my eyes.

    I suspect this is due to the SD card pausing on occasional writes - many cards will stutter occasionally for internal housekeeping,
    although I'd...
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    I noticed recently that the T4.0 and T4.1 pages...

    I noticed recently that the T4.0 and T4.1 pages have several outstanding TODO items. Not sure how important
    they are, but it looks messy, better to hide them or fix them I think, they are no longer...
  41. Repeat: Its not a reset button, it doesn't...

    Repeat: Its not a reset button, it doesn't perform a reset. It forces the Teensy into programming mode.

    To quote from the T4.1 product page:

    This is confusing if you are used to Arduinos, I...
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    The board as is requires 5V power, it cannot...

    The board as is requires 5V power, it cannot accept power on the 3.3V pin without modification: https://forum.pjrc.com/threads/64468-Teensy40-only-3-3V-power-supply?p=259469%26viewfull=1#post259469
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    If you count the peaks there are 29 per 5kHz, or...

    If you count the peaks there are 29 per 5kHz, or 172Hz, being the period of 2 audio blocks, nothing to do with power line
    frequency (you'd expect to see mainly odd harmonics of mains, not just 3rd,...
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    The problem is the 78L05 can't dissipate much...

    The problem is the 78L05 can't dissipate much heat as its a tiny TO92 package, normally
    good for 0.25W or so.
    There are clip-on heatsinks for TO92, which could improve things, but if you are...
  45. Probably just a feature of how those interrupts...

    Probably just a feature of how those interrupts behave when first enabled - gate the behaviour with a flag
    that you only set at the end of setup perhaps?


    volatile bool started = false ;
    void...
  46. The ENOB formula for a perfect ADC is...

    The ENOB formula for a perfect ADC is 6.02*bits+1.76, not just 6*bits. The rms quantization noise is sqrt(1/6)
    of an LSB not 1/2 an LSB, which accounts for the extra amount.

    When testing an ADC...
  47. No decoupling capacitors? If so fix that first -...

    No decoupling capacitors? If so fix that first - 100nF for each IC (each Hall switch is an IC), and something
    like 10--100uF bulk decoupling perhaps. Lack of decoupling can lead to all sorts of...
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    The Teensy 4's will be destroyed by 5V on any...

    The Teensy 4's will be destroyed by 5V on any pin. To convert from 5V to 3V3 I'd recommend families like 74LVC and 74LCX which run at 3.3V
    but have 5V tolerant inputs.

    A bidirectional bus driver...
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    And your code? You may have forgotten something...

    And your code? You may have forgotten something like initializing the SGTL5000

    BTW guitar picks are high impedance and inductive, thus requiring high impedance inputs to prevent loss of high...
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    Well the internal drivers in the chip are...

    Well the internal drivers in the chip are themselves MOSFETs, and they have a spread of gate voltage, so you can expect
    considerable variation between devices in the minimum workable supply voltage...
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