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  1. In C and C++ this is undefined - the compiler and...

    In C and C++ this is undefined - the compiler and linker are both free to reorder/position things however they like,
    whether static, global, local or whatever. Various optimizations may want to...
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    You need to progress the state-machines for the...

    You need to progress the state-machines for the motor all the time, not just when a noteOn/Off message arrives.

    Those messages just trigger one of the transitions in the state-machine, but all the...
  3. Can you clarify what you mean here - if you wire...

    Can you clarify what you mean here - if you wire a pin to ground it is by definition at 0V. Perhaps you are not wiring the pin at all, or not to ground, or not measuring relative to ground? Is your...
  4. Thread: Teensy 5 release

    by MarkT
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    Seen this thread?...

    Seen this thread? https://forum.pjrc.com/threads/57842-Future-Teensy-features-amp-pinout?highlight=next+teensy
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    74HCT4051, 74HCT4053, 74HCT4066, 74HCT4067, many...

    74HCT4051, 74HCT4053, 74HCT4066, 74HCT4067, many others exist, "CMOS analog switch chip" is a good search term. A key specification is the on-resistance for analog switches which can be quite high...
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    Can you show how you've wired this up? The T4.x...

    Can you show how you've wired this up? The T4.x is not 5V tolerant for instance and so you have to be careful how you apply voltages to the level converters in the Adafruit breakout.

    [ I2C = IIC...
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    That's not a range... If I can assume the...

    That's not a range...

    If I can assume the voltage is in the 0..5V range then 74HCTxx series CMOS analog switches might be a good choice.
    If the voltage could be negative you'd need to find analog...
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    You would use an analog switch chip to do that. ...

    You would use an analog switch chip to do that. What voltage range are we talking about?
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    You have a level shifter from 3.3V to 5V logic?

    You have a level shifter from 3.3V to 5V logic?
  10. Just a quick thought: Many devices that support...

    Just a quick thought:
    Many devices that support both I2C and SPI on the same pins cannot be shared as SPI - these chips respond to clocks even when CS is HIGH/inactive,
    since CS high means "I2C...
  11. This is a good resource IIRC:...

    This is a good resource IIRC: https://www.maximintegrated.com/en/design/technical-documents/tutorials/5/5450.html
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    Note that it took Einstein to sort this all out,...

    Note that it took Einstein to sort this all out, so its definitely an understandable mistake :)
  13. Yes the clocks are bussed - typically driven by...

    Yes the clocks are bussed - typically driven by the Teensy. Only the data in and out lines are kept separate in I2S, and each dataline carries 2 channels in one
    direction, so for instance the...
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    Last time I checked the ISS was in free-fall...

    Last time I checked the ISS was in free-fall...
  15. The whole audio library runs at one rate,...

    The whole audio library runs at one rate, determined by the first component initialized that uses clocking typically, such as i2s input or output.

    The interfaces for pulling samples in and out by...
  16. Merge would be AudioMixer4, crossover filtering a...

    Merge would be AudioMixer4, crossover filtering a couple of instances of AudioFilterBiquad, using Linkwitz/Riley 4th order perhaps?
    Many online filter design tools are available that will take a...
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    At 60MSPS a T4 has 10 clock cycles per sample, so...

    At 60MSPS a T4 has 10 clock cycles per sample, so no, I don't think that can fly even if you can pump the data into the processor
    via DMA (the IO clock is much slower than the processor clock,...
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    &LocalPointer is the address of the local...

    &LocalPointer is the address of the local variable LocalPointer on the stack (and has type int32_t**). Nothing to do with the value it is holding,
    which it the pointer you want to print.


    ...
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    My worry would be what's protecting the pins when...

    My worry would be what's protecting the pins when the Teensy's powered down? That would imply protection circuitry is needed anyway,
    rather than a software solution. Interference strong enough to...
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    I can confirm the rev D audio adapter only uses...

    I can confirm the rev D audio adapter only uses pins 6,7,8,10,11,12,13,15,18,19,20,21,23, GND and 3V3 as per the
    pinout table and schematic given in the docs:...
  21. Its MIDI packet type 0xF0, the MIDI clock, sent...

    Its MIDI packet type 0xF0, the MIDI clock, sent 24 times per quarter-note. Used for synchronization, presumably your MIDI source has this enabled. This is typically used if the source is something...
  22. I measure on the T4.0 (albeit with a fairly crude...

    I measure on the T4.0 (albeit with a fairly crude USB current sensor I made):



    freq aud-adapt current
    24 no 60mA
    24 yes 70mA - not using adapter
    150 no 80mA...
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    No prototype board is complete without a few...

    No prototype board is complete without a few bodges like this(!)
    I significantly reduced my error rate with PCBs by introducing a rule that I never submitted a PCB design to manufacturer
    the same...
  24. Mice use encoders, not accelerometers - (that's a...

    Mice use encoders, not accelerometers - (that's a Wii controller!). Scroll wheels are deliberately coarse
    in my experience as nominally each click is intended to jump one line of text, not a pixel....
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    g "little-g" is the acceleration due to local...

    g "little-g" is the acceleration due to local gravity, and is about 9.8m/(s^2) on the Earth's surface - its not a precisely defined value,
    but then MEMS accelerometers are very rough-and-ready...
  26. Those current values are as expected with the...

    Those current values are as expected with the current libraries.

    Power optimization is on the list I believe, but Paul has many other more pressing issues on the list IIRC. The iMXRT1062
    is a...
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    I2C lines are dark purple on the Teensy pinout...

    I2C lines are dark purple on the Teensy pinout card. 18,19,16,17,24,25 depending on which I2C peripheral you choose.

    The MCP23017 chip on that shield will not interwork with 3.3V if powered from...
  28. quit and relaunch?

    quit and relaunch?
  29. You've no actual errors in that snippet - please...

    You've no actual errors in that snippet - please post the entire verbose compiler output.
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    SCLK? Do you mean SCK on the teensy pinout card?...

    SCLK? Do you mean SCK on the teensy pinout card? That's an SPI signal, not I2S. I2S clocks are MCLK/BCLK/LRCLK.

    Unfortunately the I2S peripheral (aka SAI1) doesn't work like that, its...
  31. With I2C the bus signals are shared and...

    With I2C the bus signals are shared and bidirectional, and the MCP4725 requires logic HIGH signals to be > 0.7Vcc (3.5V if powered from 5V).
    Thus you'll need bidirectional level shifter for the I2C...
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    As I understand it laser controllers need...

    As I understand it laser controllers need DC-coupled signals, so you need to be aware some audio DACs and CODECs
    have in-built high-pass filters designed to remove DC offsets, though typically these...
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    You don't have pull-up resistors on the 6N138...

    You don't have pull-up resistors on the 6N138 outputs. Something like 2k2 to 4k7 is recommended I believe.

    Anyway there may be issues with the 6N138 and 3.3V operation, see here:...
  34. One does the driving, the other does the reading,...

    One does the driving, the other does the reading, you control the output-enable to select direction. They are the level converters,
    that's the point of using those particular families for each chip.
  35. Talking to bussed signals at 5V from a 3.3V only...

    Talking to bussed signals at 5V from a 3.3V only microcontroller is possibly a problem someone designed a chip for (haven't searched myself)

    However you can definitely combine logic families to...
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    So not fast signals. clock >---- 1k...

    So not fast signals.



    clock >---- 1k ----+-----> teensy pin
    |
    |
    2k
    |
    GND
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    Perhaps add a high-pass filter before the peak...

    Perhaps add a high-pass filter before the peak detect so that DC offsets are ignored.
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    Yes, digital signal processing is done at a fixed...

    Yes, digital signal processing is done at a fixed sample rate - you have a problem of waveform generation I think, which is not that different from
    audio synthesis. I'd suggest learning about...
  39. One problem is you are not using second order...

    One problem is you are not using second order sections (SOS) so the filter is basically numerically unstable due to the high degree polynomial used.

    Direct form realization is not normally used...
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    512 waveforms at 44.1kSPS is 22.6 million points...

    512 waveforms at 44.1kSPS is 22.6 million points per second.
    24 waveforms at 44.1kSPS is only 1.06 million points per second.

    You appear to have calculated 1024 x 1000 x 24, which makes no sense....
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    emulating the CMOS circuit doesn't do level...

    emulating the CMOS circuit doesn't do level shifting, it just provides extra protection for the destination chip.
    The source of the clock signal will be operating at high currents outside its...
  42. Can you post the actual code involved?

    Can you post the actual code involved?
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    That diagram is not a solution, its the internal...

    That diagram is not a solution, its the internal circuitry of any CMOS logic input - the diodes are part of the static electricity
    protection in the pad for that pin, they are very tiny and not able...
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    You effectively have two parallel boards with...

    You effectively have two parallel boards with ground planes, so this is like stitching groundplanes together, connect at as many
    points as possible to allow ground-return paths for signals to route...
  45. So almost certainly not a knock-off. Certainly...

    So almost certainly not a knock-off. Certainly looks damaged from that output. Poor QC?
  46. Where did you get the PT8211?

    Where did you get the PT8211?
  47. Any processing involving Fourier transforms will...

    Any processing involving Fourier transforms will require processing in blocks anyway (such as fast convolution
    or spectral analysis).

    Its general there is a balancing act between throughput and...
  48. I'm pretty sure its specific to the particular...

    I'm pretty sure its specific to the particular microcontrollers used in T3's and T4's as all the I/O stuff uses DMA hardware directly
    on those processors (so its specific to the actual processor or...
  49. For microphones you can't just use an ADC, you...

    For microphones you can't just use an ADC, you need a preamp first, microphone signals are measured in microvolts and millivolts and
    low noise circuitry is a requirement before any digital...
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    A driver that handles 4.5V to 18V has to use...

    A driver that handles 4.5V to 18V has to use thicker gate oxide in its output devices than one rated for 3V upto 8V, for instance.
    Thicker gate oxide means higher thresholds and plateaus, and more...
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