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  1. Replies
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    No, thats not really what I meant. The schematic...

    No, thats not really what I meant. The schematic of some DSP follows the signal, as in "signal processing", showing the
    flow of information through functional blocks (a schematic or high-level...
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    This is how I'd do it: long bpm =...

    This is how I'd do it:


    long bpm = encoderCount ;
    float tempo = 1e6 / (bpm / 60.0); // beat period in microseconds
    unsigned long interval = (unsigned long) (round (tempo / 24.0));

    ...
  3. Replies
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    I think this is just memory use, I see it jam...

    I think this is just memory use, I see it jam with 2 copies of the bandlimited waveform - it works with only one copy,
    and the memory is very tight:


    It works with two bandlimited waveforms and...
  4. Thread: Pwm

    by MarkT
    Replies
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    149

    You know how to get twice the bit depth by using...

    You know how to get twice the bit depth by using two PWM pins? http://www.openmusiclabs.com/learning/digital/pwm-dac/dual-pwm-circuits/index.html
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    Schematic of the DSP ought to be clear - an...

    Schematic of the DSP ought to be clear - an overview of how it all connects together as orientation - its hard work
    just reading code from cold.
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    It was probably getting out of step because some...

    It was probably getting out of step because some interrupts were dropped as they came in while the previous one
    was still being handled, like I said. You don't get indefinite length queues for...
  7. The first thing to do is check the pinout of the...

    The first thing to do is check the pinout of the encoder by buzzing it out with a multimeter or
    continuity tester. You need to start by being certain which pin is which and connect to A, B, gnd....
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    The datasheet at least draws the schematic the...

    The datasheet at least draws the schematic the right way round(!) And it has a PCB layout which you would
    do well to follow verbatim.

    Maybe add schottky protection diodes on the audio lines. ...
  9. Can you explain why this would be advantageous to...

    Can you explain why this would be advantageous to you?
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    Looks great - I'm very tempted to build one - I...

    Looks great - I'm very tempted to build one - I don't really need one, but I'm still very tempted!
    One thought is that by replacing the opamps with something like the AD8656(*) you'd have enough...
  11. Replies
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    On the ATmega328 multiple interrupts of the same...

    On the ATmega328 multiple interrupts of the same interrupt vector are discarded - not queued. It
    only queues interrupts of different types (in other words the queue has one entry per vector).
    ...
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    Could you put a block schematic for the DSP used...

    Could you put a block schematic for the DSP used in the README file, and it needs high-level comments
    and API spec. - this all goes in gui/index.html ultimately of course.
  13. You need to programmatically change the data used...

    You need to programmatically change the data used for touch event mapping when you change which form is
    presented on the screen. If you make this data-driven this will be more straight-forward. ...
  14. Replies
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    874

    Digital isolators, not opto-isolators. They are...

    Digital isolators, not opto-isolators. They are 1Mbps and up and logic inputs/outputs. They are becoming affordable and available
    in a mix of directions per chip.

    For instance:...
  15. Replies
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    167

    I did notice somewhere in the LiquidCrystalFast...

    I did notice somewhere in the LiquidCrystalFast code something like:


    digitalWrite (pin, HIGH) ; // pulse for at least 450ns
    digitalWrite (pin, LOW) ;

    which will obviously break on the...
  16. You are flushing every sample to SD card,...

    You are flushing every sample to SD card, flushing may involve several segment writes, segments are 512 bytes each.

    Better to flush regularly in time, such as every second, than every sample.
  17. Replies
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    874

    This sounds like a job for digital-isolators,...

    This sounds like a job for digital-isolators, galvanic isolation for motor drivers is good to have anyway.
  18. Replies
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    You haven't posted your code so we can't see...

    You haven't posted your code so we can't see where the problem is. You also need to show the connections you are using
    as there's more than one way to connect and some are inherently slower. The...
  19. Replies
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    T4 GPIO pins programmable output drive is from...

    T4 GPIO pins programmable output drive is from 1mA to 4mA... That's why I said 5mA is a tad high.
    I'm fairly sure it can handle 5mA with some voltage droop, but I wouldn't want to risk heavily...
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    The datasheet mentions 5mA a lot in the specs,...

    The datasheet mentions 5mA a lot in the specs, which is a tad high for T4, but ought to work at that level. I wouldn't try to push it harder
    per pin. Never connect an LED without limiting resistor...
  21. Thread: BOM Teensy 3.2

    by MarkT
    Replies
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    113

    They aren't, there's just some part numbers or...

    They aren't, there's just some part numbers or values on the layout image. For instance the USB connector has no part number
    and I wouldn't like to have to search through the many available to try...
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    Ah, those prominent caps must be decouplers...

    Ah, those prominent caps must be decouplers then...
    I think there is indeed a gap for a DC analysis object, AudioAnalyzePeak takes the absolute value, and of course
    RMS cannot be negative.
    ...
  23. Replies
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    Place in a metal box with ferrite toroid on the...

    Place in a metal box with ferrite toroid on the USB cable?

    A different T4 with audioshield and HX8357D TFT attached:
    23891

    I think that one was programmed for 150MHz
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    Link to the display details?

    Link to the display details?
  25. Replies
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    Spectrum from my SSA3021X using small B-field...

    Spectrum from my SSA3021X using small B-field probe 1cm above T4.0:
    23890

    background level from same probe:
    23889

    These are 0 -- 2.1GHz range, with T4 running at 600MHz clock.
  26. Circuit, code. Otherwise we've no information. ...

    Circuit, code. Otherwise we've no information. This could easily be either hardware or software problem from the description,
    so both are needed.
  27. Replies
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    The inputs are likely to be AC coupled.

    The inputs are likely to be AC coupled.
  28. No, I said _without scrolling_ - just output line...

    No, I said _without scrolling_ - just output line by line (its quite so nice, but its usable).
  29. I think I did measure the performance of the...

    I think I did measure the performance of the various FFT types a while back on the T4, though I guess it matters more
    on slower chips - I only have T4.0 and T3.2 at the moment to play with.

    The...
  30. Replies
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    Well I guess you just have to assume they are the...

    Well I guess you just have to assume they are the same, or close enough, and apply the equations anyway - the
    test circuit is ratiometric so the absolute resistance isn't important.
  31. You can implement a waterfall without scrolling...

    You can implement a waterfall without scrolling...
  32. Replies
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    Because chips like this are synthesized from...

    Because chips like this are synthesized from hardware description libraries shared between many other chips, the
    silicon foundaries don't start afresh for each design, they have libraries of...
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    Resistive touchscreens are an overlay, typically...

    Resistive touchscreens are an overlay, typically having a 4 wire flat-flex cable going the PCB in a different place to the
    main CoG flatflex.
  34. Hard to guess if you don't follow the forum rule...

    Hard to guess if you don't follow the forum rule and post your code... What kind of noise? Do you have any
    data/graph/spectra to show?
  35. A and #A form a pair, B and #B form a pair -...

    A and #A form a pair, B and #B form a pair - those can be routed as twisted pairs, but twisting A with B will risk
    crosstalk between the quadrature channels.

    Each RS422 pair needs termination...
  36. Comparisons of the generic fft v. the existing...

    Comparisons of the generic fft v. the existing FFT1024, for several windows, with
    input being 5 test tones at -1dB, -20dB, -40dB, -60dB and -80dB compared to full scale sine.

    23877

    Notable is...
  37. Replies
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    Unplug it, stick a multimeter on X-/X+, and...

    Unplug it, stick a multimeter on X-/X+, and Y-/Y+...
  38. Replies
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    Had another look at the XPT2046 library code and...

    Had another look at the XPT2046 library code and it doesn't calculate Z values as per the datasheet, so its
    sentitivity is inherently poor in one corner. The raw readings of x, y, z1, z2 have to be...
  39. Replies
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    The T4 is a dual issue processor so you can get...

    The T4 is a dual issue processor so you can get upto 1200 million instruction cycles per second with luck,
    but yes the clock period is 1.67ns = 1/600000000s, so 9 clocks is 15ns
  40. Timer1.initialize(10000000); // 1 Hertz ...

    Timer1.initialize(10000000); // 1 Hertz

    That's 10 million, not 1 million.
  41. Replies
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    96kSPS is the highest supported data rate...

    96kSPS is the highest supported data rate according to the datasheet, which uses MCLK = 24.576MHz (x256)
  42. You are probably not allowing dead-time between...

    You are probably not allowing dead-time between switching off one set of LEDs and switching on
    the next set - the LED junction capacitance and stored charges may be holding enough charge
    for...
  43. Replies
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    Well I'd call them completely different. I2S...

    Well I'd call them completely different. I2S requires a stable set of clocks, all phase-locked to each other and low jitter,
    running continuously and communicates a pair of digital audio channels...
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    No current limiting?

    No current limiting?
  45. Replies
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    The library has no hysteresis for Z_THRESHOLD so...

    The library has no hysteresis for Z_THRESHOLD so will inherently generate noisy z-values. This
    probably is an oversight. The Z-threshold(s) probably ought to be tweakable in the API too.

    Your...
  46. With white LEDs the high forward voltage allows...

    With white LEDs the high forward voltage allows the resistors to be smaller, but 75 ohms sounds risky - for instance
    no pin on the T4 can handle more than 4mA at max drive level, and 4mA through 75...
  47. Let me say it again: Nothing to do with pull-up...

    Let me say it again: Nothing to do with pull-up resistors. Nothing.

    And do you have current-limiting resistors? You need them to protect the output pins from overload.


    [ Here's one way to...
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    PWM hardware can't run parallel Bresenhams for...

    PWM hardware can't run parallel Bresenhams for concerted stepper motor movement, so it has to be bit banged I believe.
    (For instance for circular motion you can't set a fixed frequency...)

    T4 is...
  49. Nothing to do with pullups. With N pins you...

    Nothing to do with pullups.

    With N pins you can charlieplex N(N-1) LEDs and light at most N-1 up at once, and only then if they all share
    the same pin as the same sense (anode or cathode). ...
  50. Not sure they are documented, I read the audio...

    Not sure they are documented, I read the audio lib source in depth a while back. There may be some
    issues if you randomly play with connections, I recall somewhere there's a thread or two about...
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