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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...
  3. 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...
  4. 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.
  6. 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....
  12. 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,...
  13. 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?
  15. 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...
  16. 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...
  17. 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...
  24. 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...
  28. 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...
  29. 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...
  30. 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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    Yes I quite agree it doesn't seem to be very...

    Yes I quite agree it doesn't seem to be very friendly to the rest of the system, but I added the minimum
    extra to allow individual sample queuing, in a way that matched the existing logic. At...
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    The 1st input modulates frequency or phase...

    The 1st input modulates frequency or phase depending on the current setting,
    the 2nd input is only used for duty-cycle modulation of pulse and variable triangle waveforms.

    The phase and frequency...
  36. Ah, in your code - I suspect the reason is to...

    Ah, in your code - I suspect the reason is to keep signed and unsigned version of instructions in step with each other,
    and the shifting versions consistent with the 64 bit result versions.
    Its...
  37. BTW have you tried using an actual switch to...

    BTW have you tried using an actual switch to ground the pins - I strongly suggest touching any CMOS signal with a metal probe
    is a bad thing to do and not at all representative of actual operation...
  38. I'm not sure which multiply you mean, the...

    I'm not sure which multiply you mean, the standard biquad does 32x16 multiples which internally shift right 16,
    and then shifts these results right by a further 14.

    The coefficients are in...
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    Streuth that's nearly a fortnight!!

    Streuth that's nearly a fortnight!!
  40. if( range < 0 | range > 3) Clearly '||' or...

    if( range < 0 | range > 3)

    Clearly '||' or 'or' should be used here, its terrible style to use '|' for logical or and in many circumstances would be
    plain wrong.
    For instance:


    if (pointer...
  41. Do you have a common ground? I can only make out...

    Do you have a common ground? I can only make out 2 wires in that photo.
  42. Try using a stiffer pullup like 2k2. Capacitance...

    Try using a stiffer pullup like 2k2. Capacitance between adjacent pins couples them at nanosecond timescales. The T4 is a
    very high speed chip so its very sensitive to tiny spikes on its inputs...
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    I believe that library can use DMA, so if its...

    I believe that library can use DMA, so if its doing DMA transfer of the frame buffer its going to be
    asynchronous of the processor whatever its doing. Otherwise it may interrupt it (or if...
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    Glad to see its all integrated and working for...

    Glad to see its all integrated and working for you!
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    I've only used the system as it comes out of the...

    I've only used the system as it comes out of the box I believe there are various issues with upgrading CMSIS
    that affect other parts of the system - Paul will know the details. I used arm_rfft_q31...
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    /Applications/Teensyduino.app/Contents/Java/hardwa...

    /Applications/Teensyduino.app/Contents/Java/hardware/teensy/../tools/ -w -x c++ -E -CC -DF_CPU= -DARDUINO=10816 -DARDUINO_TEENSY32 -DARDUINO_ARCH_AVR...
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    There was a recent thread about this. Try...

    There was a recent thread about this. Try pinMode (analogPin, INPUT) in your setup() and see if that
    turns off the hysteresis circuit on the pin.
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    Yes, but you need some sort of pull-down to keep...

    Yes, but you need some sort of pull-down to keep the FET off during reset too.

    Also the SSM3K56CT as a high on-resistance of 300 milliohms - its not for high current drone motors.
    You'll probably...
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    By the way the reason for this: is that the...

    By the way the reason for this:

    is that the library routine used is radix4 - it deals only in powers of 4, not all powers of 2. The recursive
    decomposition in radix 4 requires only sign changes...
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    I also looked into this a while back, see threads...

    I also looked into this a while back, see threads
    https://forum.pjrc.com/threads/61736-Genericize-FFT-Also-window-functions-representation?highlight=generic+fft
    and...
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