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    I'm aware of teensy boards or boot loaders in...

    I'm aware of teensy boards or boot loaders in some commercial, low-moderate volume products. Higher volumes, low support costs - so I'd guess that the economics of this are far more attractive...
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    Some answers here. And more if you search this...

    Some answers here. And more if you search this forum.

    https://forum.pjrc.com/threads/23447-Teensyduino-analogReference-(INTERNAL)-same-as-default
  3. Indeed, most of it is with -E. The sketch itself...

    Indeed, most of it is with -E. The sketch itself is recompiled and then everything is relinked. It's quick, so not an issue - but I expected it to do nothing (since no files have been touched). ...
  4. I'm curious, why is it recompiling all kinds of...

    I'm curious, why is it recompiling all kinds of things that didn't change? It happens for me too (Linux, just by hitting verify twice).
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    I've blown two speakers. In both cases, the...

    I've blown two speakers. In both cases, the tweeter, so DC offset had nothing to do with it.
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    Generally yes, sending audio over ethernet and/or...

    Generally yes, sending audio over ethernet and/or IP is increasingly popular.

    Teensy doesn't have much support for it, but there is this:
    ...
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    I have a philosophical question about clock sync....

    I have a philosophical question about clock sync. Which is better for teensy related, separated audio clock use cases?

    a) just match rates
    b) match rate and phase (like a PLL). If clock A...
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    I've seen debug log messages like "value too...

    I've seen debug log messages like "value too high", which leaves me lost as to what it means and how to fix it.

    For some use cases, consider using something like:

    LOGD("%s %d %s", "Debug",...
  9. Here is some very general advice. Learn the...

    Here is some very general advice. Learn the basics of LTSpice and use it, even for simple circuits. Never perfect, but it's a great way to learn things like "what would happen if I injected a...
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    I have some code working that will take a...

    I have some code working that will take a periodic input from any source at any frequency and adjust the teensy audio clock to match it. For example, I'm syncing to a PC sending a single byte via...
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    I tried it and while changes to...

    I tried it and while changes to CCM_ANALOG_PLL_AUDIO_NUM clearly changes the clock rate, it isn't a simple ratio. You could use trail and error to find the right value. Or use the c1 value from...
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    I think so, but let us know. I'm working on...

    I think so, but let us know.

    I'm working on some code that will calculate the correction ratio to apply from any kind of periodic communication. But a fixed ratio is fine for some uses.
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    AUDIO_SAMPLE_RATE_EXACT is a compile time...

    AUDIO_SAMPLE_RATE_EXACT is a compile time setting. You are looking for a run-time clock change, which has to be done differently.

    Using Paul's recent discovery, should be something like:
    ...
  14. > a virtual GND of 1.65V and power the AD8224...

    > a virtual GND of 1.65V and power the AD8224 with +-3.3V)?

    You would want the AD8224 to operate without a virtual ground. And the 2nd stage needs power too. Probably not worth the changes,...
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    It could be "what the teensy clock registers are...

    It could be "what the teensy clock registers are going to be initially set to". Which, glancing at AudioStream.h, is already sometimes a non-integer number.
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    I could see a use for an...

    I could see a use for an AUDIO_SAMPLE_RATE_NOMINAL that would always be 44100, 48000 or etc.
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    I see the clock setting code in these files. ...

    I see the clock setting code in these files. So IMO, yes, it should be consolidated into a single function. Using a double.

    ./avr/libraries/Audio/output_mqs.cpp: int fs =...
  18. You could also add an inverting charge pump - the...

    You could also add an inverting charge pump - the AD8224 will run on 3.3V and -3.3V.
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    Now we need a PTP like protocol to exchange clock...

    Now we need a PTP like protocol to exchange clock rate information between hosts. Preferably one that is flexible about what the transport is. Serial, RF, ethernet, hardware pin, etc. Is there...
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    > no more sliding clocks now Just to be clear,...

    > no more sliding clocks now

    Just to be clear, your clocks are still sliding. But perhaps at such a low rate that you don't care.
  21. Your first graph has a scale that goes negative. ...

    Your first graph has a scale that goes negative. But in single ended mode, the output of the ADC is unsigned. Mix up signed and unsigned and you get strange jumps at 32767.
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    > allows 0%error for all std frequencies More...

    > allows 0%error for all std frequencies

    More precisely, 0% error from the source. But a crystal source always has error, so all you can ever do for the absolute rate is "close enough". Ie, a...
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    Sounds good. Change the clock setting code to...

    Sounds good. Change the clock setting code to use a large denominator and floating point. Then anyone wanting to tweak rate can a) change AUDIO_SAMPLE_RATE_EXACT at compile time or b) change...
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    I toggled CCM_ANALOG_PLL_AUDIO_NUM between 2240...

    I toggled CCM_ANALOG_PLL_AUDIO_NUM between 2240 and 2241 every second with no audible effect. This is with SPDIF output to an external DAC.

    For most use cases, only small changes are needed -...
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    Nice! Kudos for not trusting the manual. ...

    Nice! Kudos for not trusting the manual.

    Add something like PTP and you can get sync, even over wireless.
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    I see Frank's point. Not sure what I did wrong...

    I see Frank's point. Not sure what I did wrong when I tested it and got a better match between my PC and teensy rate. Perhaps a misleading random change in one of the clocks.

    Looks like it...
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    I suspect that your best bet is to use what you...

    I suspect that your best bet is to use what you have but add more buffering (to cover the gaps).
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    As Paul explains, the decimal portion of...

    As Paul explains, the decimal portion of AUDIO_SAMPLE_RATE_EXACT *is* used. On a T4, you can use it (at compile time) to get two asynchronous clocks to be close to the same rate. But clocks change...
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    You might be able to adapt the "flasher4" code to...

    You might be able to adapt the "flasher4" code to do this.

    https://forum.pjrc.com/threads/29607-Over-the-air-updates/
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    > We like to detect a clipped audio signal coming...

    > We like to detect a clipped audio signal coming from the mixer

    Remko wants to detect clipping that occurred in the mixer or upstream of it. The signal level is likely to be fine once it gets...
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    Another common problem is noise from ground...

    Another common problem is noise from ground loops. Don't reference to any noisy ground that you don't have to. Use outputs from an isolated teensy+audio adapter as balanced signals into...
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    Clipped signals produce more high frequency...

    Clipped signals produce more high frequency energy - which blows tweeters.

    The histogram method here sounds promising. Or do a FFT and compare 3khz and above energy to energy below 3khz.
    ...
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    It's easier if you make the Teensy/ESP a fixed ip...

    It's easier if you make the Teensy/ESP a fixed ip address web server on your wifi network and then have the PC poll it via http.
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    Do #1 - teensy headphone jack into mixer line...

    Do #1 - teensy headphone jack into mixer line input.
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    What is the feasibility of adding virtual files...

    What is the feasibility of adding virtual files to MTP? For example, "memory", which would provide read access to all memory in the teensy?
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    Any easy, standards based way for a PC to access...

    Any easy, standards based way for a PC to access non-volatile data (eeprom or other) in a teensy would be useful. Perhaps virtual files accessed via MTP?

    For example, I run audio convolution...
  37. Thread: i.MX RT1170 ??

    by jonr
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    The NXP i.MX RT1176 eval board should be more...

    The NXP i.MX RT1176 eval board should be more widely available in February.
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    Besides the clear need for more structure on top...

    Besides the clear need for more structure on top of teensy non-volatile storage, there is the barrier-to-change business issue. It should be easy to port software from ESP32 to teensy. The reverse...
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    Seems like such a library should be built on top...

    Seems like such a library should be built on top of teensy's EEPROM code. For many uses, far less than 64K is adequate.
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    This is worth reviewing: ...

    This is worth reviewing:

    https://arduino.stackexchange.com/questions/57645/trouble-configuring-arduino-due-spi-to-adc
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    > I need to acquire 200,00 samples to have a...

    > I need to acquire 200,00 samples to have a correct 100khz samplerate

    I'd word it as "the setting and library will cause the ADC to acquire 200,000 samples/sec to produce the correct output rate...
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    It tries to produce the derived sample rate that...

    It tries to produce the derived sample rate that you specified (100,000), no matter how much averaging you do. In your example, 200,000 samples/sec need to be taken which is then reduced to 100,000...
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    Did you try changing AUDIO_SAMPLE_RATE_EXACT as...

    Did you try changing AUDIO_SAMPLE_RATE_EXACT as suggested in #4?
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    Regarding clock rate sync between two...

    Regarding clock rate sync between two non-wired-together sources, just adding a GPS module to each one might be easier than implementing PTP.
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    I find the manual quite dense, but as I see it, a...

    I find the manual quite dense, but as I see it, a clock can be applied to the SPDIF_EXT_CLK pin and this can be used as the SPDIF clock, Then the SAIs can use the SPDIF clock as their clock (see...
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    > will that slow things down If you are...

    > will that slow things down

    If you are concerned about speed, then I encourage you to learn how to measure speed. Search this forum for "ARM_DWT_CYCCNT".
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    Other than using the hardware audio inputs (I2S,...

    Other than using the hardware audio inputs (I2S, spdif), I'm not aware of any way to get a teensy audio output to precisely sync with an asynchronous clock from another source. I think you could...
  48. The demo here sounds quite effective: ...

    The demo here sounds quite effective: https://www.seeedstudio.com/ReSpeaker-Mic-Array-v2-0.html

    On the other hand, if the source is at a fixed position, it would be interesting to hear how well a...
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    Try turning off interrupts with cli().

    Try turning off interrupts with cli().
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    Frequent overruns unless I patch the feedback...

    Frequent overruns unless I patch the feedback code in usb_audio.cpp.

    https://forum.pjrc.com/threads/61142-USB-Audio-Frame-Sync-on-Teensy-4-0
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