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Type: Posts; User: MarkT

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  1. Replies
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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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    17,551

    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...
  6. 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...
  7. 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...
  8. 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.
  9. 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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    371,091

    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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    1,277

    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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    788

    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...
  18. Thread: Teensy 4.0

    by MarkT
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    233

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

    That chip seems to support I2C fast mode - are you already using this?
  19. 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.
  20. Clearance between the boards?

    Clearance between the boards?
  21. 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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    5,274

    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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    3,159

    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
  32. 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"
  34. A cryptographic hash function can be used to...

    A cryptographic hash function can be used to detect repetitions of previous states without
    having to store all the previous state - perhaps only 256 bits per repetition.

    The chance of different...
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    The correct way to run something every 50us is...

    The correct way to run something every 50us is this:


    #define PERIOD 50

    unsigned long prevtime = 0L;

    void loop ()
    {
    if (micros() - prevtime >= PERIOD)
  36. Searching by content is a useful operation in its...

    Searching by content is a useful operation in its own right, not just in the context of programming languages, a generic
    tool for search is usually much easier to learn and use than learning a...
  37. I suspect there are implications for distortion...

    I suspect there are implications for distortion and noise, especially for low-impedance load like a headphone - basically this is not
    what the chip was designed for. Perhaps you need a different...
  38. If the boards are identical and programmed...

    If the boards are identical and programmed identically I would expect the LEDs to light identically.
    Yes the pin drives the LED so it will light up when there's activity. LEDs light up in...
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    Current only flows when the load demands it. A...

    Current only flows when the load demands it. A 50A regulator isn't going to damage a 1mA part(!) - but if the voltage was
    too high, that's a different matter...

    The 78xx series is not an LDO...
  40. You can get standalone file content search tools,...

    You can get standalone file content search tools, including versions of the original grep unix tool https://en.wikipedia.org/wiki/Grep
    No idea how anyone would cope without such a tool frankly!
  41. The supply voltage is the limitation, that chip...

    The supply voltage is the limitation, that chip has an output full-scale of 1Vrms (2.83V peak-to-peak) at 3.3V supply - theres no
    way to get much more than that from a single 3.3V rail.

    An opamp...
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    I think this is the pin being in Schmitt-trigger...

    I think this is the pin being in Schmitt-trigger mode, ie deliberate hysteresis circuit is active. I suspect this may
    be the chip default at reset (to prevent power drain from floating inputs). I...
  43. You haven't posted your code. Can you confirm...

    You haven't posted your code.

    Can you confirm the boards are identical, programmed identically? Normally the quiescent SCLK will be determined by the
    SPI mode in use.

    Are you expecting the...
  44. Does the code stop without the print debugging? ...

    Does the code stop without the print debugging? Where did you put the debugging?

    With no memory or too little memory the code will run but see the result of allocate() return NULL. This is...
  45. The time constant of I2C bus lines doesn't...

    The time constant of I2C bus lines doesn't magically change with voltage, there is no reason for
    the pullups to differ in value at 3.3V from 5V, the frequency of operation and total bus capacitance...
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    The longer the cable the more the need for...

    The longer the cable the more the need for protection circuitry, as long cables pick up more noise from the surroundings. A simple
    10--100nF ceramic cap to ground may be enough for many purposes,...
  47. Its wise never to let clocks or chip-select lines...

    Its wise never to let clocks or chip-select lines float - otherwise the chip might randomly configure after power up and
    before the microcontroller has set its output pins as outputs. Hardware...
  48. Everything about a 2MHz converter is crucial,...

    Everything about a 2MHz converter is crucial, capacitors, inductors, layout - I suggest just use the parts and layout
    from the datasheet verbatim. This chip generates very fast edges (< 10ns) with...
  49. Is the current handling of the inductor high...

    Is the current handling of the inductor high enough? If it saturates its bad news. Did you go with
    one of the ones listed in the datasheet? And follow the datasheet example layout?

    Its not a...
  50. Volume is done with the amp object, tone controls...

    Volume is done with the amp object, tone controls are trickier as you'll have to figure out the filter response you
    want and encode that with the biquad filter object.

    The pots would be read...
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