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  1. OK, I did some homework on M.2 (which I probably...

    OK, I did some homework on M.2 (which I probably should have done before posting!). It's a larger industry standard than I realized - and fair to assume it would have been axed by now if reliability...
  2. MicroMod Teensy - Theoretical pin+socket longevity

    Hi all,

    I have a na´ve question. I have never developed a board with a socket that directly interfaces with PCB pads. I grew up blowing into Nintendo cartridges to make games run, so I have an...
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    IMPORTANT: Please use the updated OSHPark links...

    IMPORTANT: Please use the updated OSHPark links in the PCB Readme, here.
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    I just posted v1.1 of this board in the...

    I just posted v1.1 of this board in the repository, solving the previous stability issue with DAC2 HD.
    The fix was to add a 4-component USB power supply filter borrowed from an FTDI circuit note,...
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    For the record, I started a thread on this topic...

    For the record, I started a thread on this topic here. I'm currently using a workaround on the MATLAB side that loops the serial read and write functions with no more than 200 bytes per read or...
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    Awesome, thanks Frank! A small update - I...

    Awesome, thanks Frank!

    A small update - I discovered that the crackling issue on the top-mount version of the board only affects DAC2 HD - not DAC2 Pro or DAC+.
    I've updated OSHpark and Github...
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    T4 Pin Drive Strength

    Hi all,

    I'm hoping to learn whether someone has already developed a function to set the drive strength, speed and other configurable parameters of Teensy digital pins (esp. T4.0 and 4.1)
    ...
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    I added example USB Passthrough...

    I added example USB Passthrough sketches for DAC2 Pro and DAC2 HD.
    This effectively turns either HiFiBerry board into a 44.1kHz 16-bit USB sound card for the PC. To load these example sketches, you...
  9. And I'll be darned. It WAS a ground loop. The...

    And I'll be darned. It WAS a ground loop.
    The glitches are gone if I record with the NI board on my laptop while the Teensy is powered from a different PC.

    Thanks Paul!!
  10. I had assumed that the spikes were driven by...

    I had assumed that the spikes were driven by digital noise in the I2S signal - but you do make a good point about my sanity check - the NI USB card and the ASUS Xonar U7 were both grounded to the...
  11. I don't suspect a current issue - why would pin44...

    I don't suspect a current issue - why would pin44 cause more current to be drawn by an audio board than the other built-in SD pins?
    If the line out has digital filtering enabled somewhere by...
  12. Oddly enough, no! At first pass, the line out...

    Oddly enough, no! At first pass, the line out pins don't seem to have the issue. I expected to see it, since I saw them on the headphone channel and two separate PCM series audio DACs. Does the line...
  13. I found a reason why it may have evaded...

    I found a reason why it may have evaded detection:
    At full volume on the SGTL (sgtl5000_1.volume(0.8);), the glitch is masked almost entirely by the noise floor:

    23824

    It's more salient at...
  14. OK, maybe it's a typo in the pinout diagram. I...

    OK, maybe it's a typo in the pinout diagram. I was hoping not!

    I should add - this glitch is practically inaudible to me with headphones at standard listening levels. The glitches are only 2-3x...
  15. Hi Frank, For all tests except for I2S2, I...

    Hi Frank,

    For all tests except for I2S2, I plugged the Teensy 4.1 board directly into the Teensy audio board using pin headers.

    From the pinout diagram, it looks like pin 44 is a clock pin for...
  16. Thanks Paul! I had in mind to use I2S2 by...

    Thanks Paul!

    I had in mind to use I2S2 by itself, to get around this issue - but I ran an SD test this morning using I2S2 (with some comical prototyping wire remapping) and got the same result.
  17. Looks like the same interference from pin 44...

    Looks like the same interference from pin 44 affects audio on I2S2:

    23821

    The noise floor is higher (prototyping wires) but the glitch amplitude is the same (compare to plot from my first post,...
  18. I noticed that slave mode on I2S2 is commented...

    I noticed that slave mode on I2S2 is commented out in output_I2S2.cpp:
    // void AudioOutputI2S2slave::begin(void)

    Is there a known reason why it won't be able to work in a future update? Or is it...
  19. Thanks, Defragster! I configured each pin as...

    Thanks, Defragster!

    I configured each pin as OUTPUT, and set PWM frequency to 1MHz.
    Then, while a zero-amplitude sine wave was playing, I set each builtin-SD pin to 50% duty cycle for a 3ms...
  20. I ran one more test, to rule out my acquisition...

    I ran one more test, to rule out my acquisition hardware.

    Until now, all of the data was captured with an NI USB-6211 DAQ board sampling at 200kHz, but for some reason the distortion was difficult...
  21. I ran a few more tests to constrain the possible...

    I ran a few more tests to constrain the possible causes of the interference. Here's what I found:

    -File reading does not interrupt PWM signals from T4.1 pins
    -File reading does not interrupt an...
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    My ten cents: you're paying for the peripherals...

    My ten cents: you're paying for the peripherals and proprietary board layout, not the DAC IC. There are plenty of breakout boards for audio DACs, but they don't do high end power supply filtering,...
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    I'm not sure that a 100-ohm resistor could...

    I'm not sure that a 100-ohm resistor could account for the difference - the two (working and buggy) boards have identical wiring, with the only difference being trace length. I used thick traces, so...
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    Hi Frank B, You were correct - it was a...

    Hi Frank B,

    You were correct - it was a hardware issue!

    The last code I posted was a stab at adapting the problematic code from the HiFiBerry to the SGLT, albeit in Teensy-as-I2S-master mode....
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    Hi Paul! The overtone was fixed by increasing...

    Hi Paul!

    The overtone was fixed by increasing AudioMemory to 50.
    With AudioMemory as high as 250, I'm still getting crackling on the right audio channel on the HiFiBerry boards.
    The original...
  26. Hi WMXZ, With the sketch I posted,...

    Hi WMXZ,

    With the sketch I posted, AudioMemoryUsageMax() returns 2.
    I set AudioMemory(50) and reduced the SD write buffer from 64k to 1k - same interruption every 100ms (though its duration was...
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    I posted a thread in the audio forums, but since...

    I posted a thread in the audio forums, but since it concerns 1.54 beta 6 and the new integration with SDFat, I'm linking to it here.
    The 5 second version is that calling SDCard.read() in SDIO mode...
  28. Interference between SDFat/SDIO and I2S on T4.1

    Hello,

    I'm seeing audio DAC output glitches when reading from Teensy 4.1's onboard microSD card using SDIO.
    I'm using Teensyduino 1.54 beta#6.
    Here's a sketch that reproduces the issue:

    ...
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    Good news - the board now works with HiFiBerry...

    Good news - the board now works with HiFiBerry DAC2 HD!
    I also worked out the remaining issues with I2S slave mode on DAC2 Pro.
    The updated code is on Github, here.

    The signal quality looks...
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    Teensy 4 + HiFiBerry DAC

    Hi all,

    Like many Teensy 4 users, I've been eager to funnel all of that computing power into some slick HD audio.
    This past year, HiFiBerry released two next-gen audio cards for Raspberry Pi -...
  31. Dropped data from T4.X but not T3.X using MATLAB to read output of serial.write()

    Hi,

    I'm trying to nail down a USB data transmission issue I'm seeing with Teensy 4.0 and 4.1.
    It has been a heck of a bug to chase.

    Here's some background info:
    -I'm using Windows 10 OS,...
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    I figured it out. In the end, I had to add the...

    I figured it out. In the end, I had to add the set_audioClock() function and 1-2 other minor mods.
    Here's my complete sketch, tested on T4.1. I changed the sound to a square wave sweep, which is...
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    Hi Neal, Is your full code available...

    Hi Neal,

    Is your full code available somewhere?
    I'm familiarizing myself with with this level of T4's audio interface to achieve low latency i2s writes, and this looks like just the thing to...
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