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  1. > printf("uint32_t var : %"PRIu32"\n", u32x); ...

    > printf("uint32_t var : %"PRIu32"\n", u32x);

    Nice, thanks. But I tried it on a teensy and memory usage went way up.
  2. My understanding is that output pins should be...

    My understanding is that output pins should be limited to 10mA. Add a mosfet if you need more.
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    While it can be done from Paul's schematics and...

    While it can be done from Paul's schematics and advice (https://www.pjrc.com/store/ic_mkl02.html) alone, you will be better off starting with one of the published complete designs (schematic, PCB...
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    > 66 MHz effective Interesting, slower than I...

    > 66 MHz effective

    Interesting, slower than I thought. I'd guess that an unrolled loop of [*d = GPIO1_DR] is probably most similar to how fast DMA can run. If the DMA is triggered by a pin...
  5. Are the Raspberry Pi's GPIO pins set to maximum...

    Are the Raspberry Pi's GPIO pins set to maximum source and sink current drive capability?

    You could put a RC filter on the teensy end.
  6. Account for it being quad SPI.

    Account for it being quad SPI.
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    @dgranger I'm curious how fast you can go if...

    @dgranger

    I'm curious how fast you can go if you don't use DMA and just poll? Ie, wait for pin change, read/store GPIO, loop.
  8. While 9216x2 taps is OK, it could go higher if...

    While 9216x2 taps is OK, it could go higher if DMAMEM could be used for some of the large arrays (eg fmask). But with USB input and spdif output, this causes some static. Any idea why or how to...
  9. As I recall, the pedvide ADC library has the...

    As I recall, the pedvide ADC library has the obnoxious side effect of turning on interrupts.
  10. Here is the alpha code if you need two impulse...

    Here is the alpha code if you need two impulse responses applied to two channels:
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    I think you want: float32_t inbuf; ...

    I think you want:

    float32_t inbuf;

    myFile.read(&inbuf, sizeof(inbuf));
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    I always get 223.98 when using a double. "%.2f"...

    I always get 223.98 when using a double. "%.2f" works even with a float.
  13. > This seems all pretty unstable. Possibly...

    > This seems all pretty unstable.

    Possibly related - I found the audio+midi+serial option to not work with T4.0 and Linux. Serial alone or audio alone (except for volume control) has been fine.
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    There is lots of info about time accuracy on this...

    There is lots of info about time accuracy on this forum. Consider doing your own temperature compensation. Or using the RTC.
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    Another issue/bug: any call to usb1.volume()...

    Another issue/bug: any call to usb1.volume() causes the audio device on linux to stop working.

    * Linux Mint, Arduino 1.8.13, TD 1.53
    * Teensy 4.0 with toslink/spdif3 output
    * USB Audio in
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    It probably helps (lower jitter?), but experience...

    It probably helps (lower jitter?), but experience says it isn't necessary.
  17. I have code to alpha test if anyone is interested.

    I have code to alpha test if anyone is interested.
  18. Agreed, unless someone with better understanding...

    Agreed, unless someone with better understanding wants to help, creating a second fmask array and then running the existing multiply/ifft process twice better fits my limited understanding of this...
  19. > both IRs (for left and right speaker channels)...

    > both IRs (for left and right speaker channels) are both stuffed into the maskgen buffer

    I thought about this, but if this would work, how does it work as the code is now? The imaginary/odd...
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    +1 on what Paul said. Since this keeps coming...

    +1 on what Paul said. Since this keeps coming up, here is one that can be copied. Note the guard ring and single ground connection point. Not shown is the continuous ground plane under it. ...
  21. Ran into an issue - speaker/room correction is...

    Ran into an issue - speaker/room correction is normally done with a separate impulse for each channel. And I don't understand the code well enough to change it.
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    That wiring worked, but wasn't bright enough for...

    That wiring worked, but wasn't bright enough for some DACs. This works correctly.
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    Has anyone used T4 Serial+Midi+Audio with Linux? ...

    Has anyone used T4 Serial+Midi+Audio with Linux? DD4WH (OS unknown) reported the opposite problem (Audio alone didn't work).
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    I think your crystal is sharing a line with...

    I think your crystal is sharing a line with something else. I wouldn't do that.
  25. Will do once I'm done. More on DRC here: ...

    Will do once I'm done. More on DRC here:

    https://en.wikipedia.org/wiki/Digital_room_correction#:~:text=Digital%20room%20correction%20(or%20DRC,of%20a%20sound%20reproduction%20system.

    It does...
  26. Thanks (for the help and the code). I found it...

    Thanks (for the help and the code). I found it was necessary to use AudioMemory(20). Sounds good now. Might be worth using 20 (or more?) in your code.

    The goal is to do digital room...
  27. I don't use I2S at all, but restoring that rate...

    I don't use I2S at all, but restoring that rate line made no difference. A big clue - disabling all the convolution code and just taking samples, converting to float and then back also has the...
  28. I made minimal changes to use USB input and...

    I made minimal changes to use USB input and spdif3 output and I get lots of static (setup works fine without convolution). Tried two difference versions (first was 09/11/2019). Any suggestions or...
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    Linux audio device bug? + toslink on T4

    When I run this program with the USB type set to Serial/MIDI/Audio, there is silence. I change to USB type "Audio" and it works well. T4, OS is Linux Mint, Teensyduino 1.53. Is it possible to have...
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    More info here: ...

    More info here:

    https://forum.pjrc.com/threads/62921-Help-with-Teensy-3-2-DIY-Project
  31. > do Serial.flush() I've been caught by the...

    > do Serial.flush()

    I've been caught by the fact that Serial.flush() doesn't actually wait until the data is seen by the PC. For that you also need a delay.
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    Due to pin-out differences (a TCXO needs power),...

    Due to pin-out differences (a TCXO needs power), I assume this is for a custom teensy design? If so, I'd encourage you to design it to use a VCXO. This would allow software to trim for even better...
  33. Thread: audio clock slip

    by jonr
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    There is frequency accuracy and jitter. ...

    There is frequency accuracy and jitter. Hopefully nobody is thinking that something like a 10 ppm difference in frequency is audible (unless it causes a buffer under-run). Jitter does effect sound...
  34. Thread: audio clock slip

    by jonr
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    NTP works better than I guessed. I run chrony on...

    NTP works better than I guessed. I run chrony on my PC and it reports that the system clock wanders around 5 ppm fast but is corrected to .01 ppm.

    My sound card's rate is a bit off - I have to...
  35. Thread: audio clock slip

    by jonr
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    I'm no expert, but I see these choices for audio...

    I'm no expert, but I see these choices for audio rate sync where there is a teensy and other audio clocks:

    a) Use a shared clock source. Certainly possible if the teensy is the clock source,...
  36. Thread: audio clock slip

    by jonr
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    > the host is responsible for adjusting the data...

    > the host is responsible for adjusting the data rate to match the device's requirement

    Understood, and helpful to know this. But if the data is coming into the PC from some other source (eg,...
  37. Thread: audio clock slip

    by jonr
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    Another option would be to flip between PLL4 and...

    Another option would be to flip between PLL4 and PLL5. I don't know if that would cause any audible glitch.

    It does appear that when the crystal is exactly 24 mhz, the system will produce...
  38. Thread: audio clock slip

    by jonr
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    Regarding PLL4, it looks like it needs to be...

    Regarding PLL4, it looks like it needs to be stopped and restarted to change. But there are periods when an audible glitch would be harmless. For example, on startup. Ie, run for a few minutes...
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    As much as possible, switch to digital audio...

    As much as possible, switch to digital audio transmission.
  40. Thread: audio clock slip

    by jonr
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    audio clock slip

    Just getting started with teensy audio. I imagine that the teensy 4 derives its i2s clock from something that isn't an exact multiple of 44100. So if I'm receiving real-time audio on a PC at 44100...
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    Or convert to SPDIF/toslink output. Then you...

    Or convert to SPDIF/toslink output. Then you have all digital up to a point with no electrical link.
  42. I'd run the MCP3008 at 3.3V, reducing analog...

    I'd run the MCP3008 at 3.3V, reducing analog input voltages with a voltage divider if they are > 3.3V.
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    Using the ADC differential inputs and providing...

    Using the ADC differential inputs and providing matched input paths (same routing, same filtering, etc for both lines) is helpful.
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    I think something like MISRA C++ would be best...

    I think something like MISRA C++ would be best for beginning embedded programmers. Not just for a job, but for better (more reliable, easier to maintain, etc) programs.
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    I'm curious about your thoughts on teaching C vs...

    I'm curious about your thoughts on teaching C vs starting with C++. IMO, better not to have to unlearn bad habits.
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    It's not the case here, but if the input were...

    It's not the case here, but if the input were capacitor coupled with no resistor, the input voltage would rise to be a huge error.
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    I'd go straight to learning C++, even if many...

    I'd go straight to learning C++, even if many embedded programs are in C. It will encourage better code.

    IMO, it's important to have academic, experimental and a commitment to keep improving.
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    > Its widely used for Modular Synth Modules for...

    > Its widely used for Modular Synth Modules for input protection of digital Modules

    Looks to me like the op amp before it (rated for VCC– + 36) is providing the protection.
  49. I suspect that the software (and the laser...

    I suspect that the software (and the laser characterization) included in the evaluation kit (MAX98390EVSYS) is useful.
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    > MPC6002 ... can be used for clamping What...

    > MPC6002 ... can be used for clamping

    What happens when 5V gets applied to the MPC6002 analog input which is rated to a max of VDD + 1.0V?
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