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  1. Can you use a USB midi dongle connected to the...

    Can you use a USB midi dongle connected to the host? This will show up as an available USB MIDI device to JUCE, then talk to the Teeny over the usual MIDI connectors.

    Example USB midi dongle
    ...
  2. There is a way to restructure the metadata in a...

    There is a way to restructure the metadata in a fairly backwards compatible way. I tried this out and it it worked on my setup.

    1) Modify the audio_block_t to contain (int16_t*) instead of a fixed...
  3. The aversion to memcpy is every single word...

    The aversion to memcpy is every single word copied takes multiple CPU instructions from the various load-stores. At 44 Khz, you're talking a couple hundred thousand instructions per second for a...
  4. Thanks WMXZ for taking the time to read and...

    Thanks WMXZ for taking the time to read and comment, the help is appreciated.

    I looked over the output_i2s.cpp, you're right WMXZ, the output_i2s.cpp creating a local 32-byte aligned i2s_tx_buffer...
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    You might want to create your own separate...

    You might want to create your own separate project thread for discussing your mixer design, it may get more views that way.
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    I don't think you're missing anything. Memory...

    I don't think you're missing anything. Memory comes down capacity, latency and throughput (let's ignore power for now). So I guess it comes down to how much of your customer base needs something...
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    ISSI is probably the cheapest alternative (well,...

    ISSI is probably the cheapest alternative (well, a little bit cheaper than Cypress) ignoring all the Chinese-only market stuff. You can get 64Mbit for about $5 USD in production quantities. Would I...
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    FORM FACTOR - keeping the T3.6 form factor would...

    FORM FACTOR - keeping the T3.6 form factor would be great

    RAM - adding a big chunk of reasonably fast ram would be ideal. A single HyperRAM chip on board would be my suggestion in 64Mbit or...
  9. Once again, thanks for your time Paul. - just to...

    Once again, thanks for your time Paul.
    - just to be clear, please note my suggestion is the AUDIO_BLOCK_SAMPLE sized audio data buffers (audio_block_t.data) must be be 32 BYTE aligned for DMA, not...
  10. Hi Paul, thanks for the reply. I've looked at the...

    Hi Paul, thanks for the reply. I've looked at the cache functions in quite some detail as I've been investigating this issue for about 2 months so I'm happy to wait a few more weeks. I've also had...
  11. Any developers who contributed to the Audio...

    Any developers who contributed to the Audio library or DMA development care to comment on this? I'd like to get some validation or discussion before submitting a bug report on github.

    Once again,...
  12. I've been looking at lot at the T4 memory...

    I've been looking at lot at the T4 memory structure lately as i've been having problems with cache coherency.

    @defragster, perhaps you can clear up any misconceptions.

    I'm pretty sure the TCM...
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    You can also use SPI ram for delay. My audio...

    You can also use SPI ram for delay. My audio board uses 4Mbit chips. One of these chips gives about 6 seconds of single-channel delay, the equivalent of 2048 audio blocks. You can use the SPI...
  14. Cool! In order to use the built-in allocate() and...

    Cool! In order to use the built-in allocate() and release() functions (which would let you avoid implementing a pool manager) you must inherit the AudioStream class, otherwise you'll need to hack the...
  15. Okay, I was able to reproduce this issue with the...

    Okay, I was able to reproduce this issue with the Teensy Audio Shield. Maybe someone with a working Teensy 4.0 and audio shield using LINE IN left can give this a try?

    The sketch is written to...
  16. Teensy 4.0 problem with DMA to/from OCRAM interacting with Audio library

    After months of struggling to get DMA SPI memory working with the T4 OCRAM I think I finally found the problem, and I think it's in AudioStream.h. Basically, I'm getting audio buffer corruption when...
  17. SPI1 with DMA is only supported on 3.5/3.6/4.0

    SPI1 with DMA is only supported on 3.5/3.6/4.0
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    I'm not sure how you could possibly think you got...

    I'm not sure how you could possibly think you got scammed. Mixed signal (analog and digital) design is tough, period. The built-in ADC is not intended for high quality audio applications like guitar...
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    The schematic is available for free in the...

    The schematic is available for free in the datasheet found on the product page. You are welcome to take a look at the preamp and analog power design for use in your own circuit.
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    My TGA Pro audio shield has everything on board,...

    My TGA Pro audio shield has everything on board, ready to go, no soldering needed. Properly designed power and layout to isolate the analog from the digital stuff as much as possible. It recently...
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    You must have a ground between the boards...

    You must have a ground between the boards otherwise they won't be able to communicated with each other. Even if you cut the ground in the cable, they'll find a ground between them somehow, but it...
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    The link to the JAVA source code implementation...

    The link to the JAVA source code implementation is here.

    The rotation applied to the phaser in the paper is given as

    -i * (b-ma) * p * 2*PI / (m * O * N)

    The correct phase shift is


    //...
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    The paper published by the Ocean authors had a...

    The paper published by the Ocean authors had a typo in the phase calculation. The correct phase adjustment and demodulation function can be obtained from their public JAVA code of the algorithm, in...
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    Actually, now that I look closer, it's not the...

    Actually, now that I look closer, it's not the DMAMEM attribute that seems to make it work. Putting them in static memory works too. It's just the heap memory that doesn't work. So I guess the...
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    Well after weeks messing with the DMA I'm ready...

    Well after weeks messing with the DMA I'm ready to pull my hair out. I was able to get it to work with T4 only by declaring the buffers as DMAMEM instead of allocating off the heap. I tried using the...
  26. Two possibilities: #1 When you adjust delay,...

    Two possibilities:

    #1 When you adjust delay, you are still jumping between discrete delay times (resolution 1/44100 seconds) which in itself causes aliasing. When people design chorus/flanger...
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    Many of the Teensy's have a built in ADC, though...

    Many of the Teensy's have a built in ADC, though it's only 12-bit. Many people use it for audio when they don't need high quality. Are you using a Teensy 3.5/3.6 and running out of pins? If not,...
  28. I'm actually a hardware guy. :) 5 years...

    I'm actually a hardware guy. :)

    5 years digital ASIC design, 11 years FPGA and electrical schematic/PCB design. It's only the last few years (about 3) I've shifted to software as the work I do...
  29. I see both shift operators and bit functions a...

    I see both shift operators and bit functions a lot, neither is particularly readable or less readable to me. The IMPORTANT thing is to not use magic numbers in your code.


    // GOOD, because the...
  30. Even with the pot not moving, the analog read...

    Even with the pot not moving, the analog read value will still be jumping around a lot due to noise, which is the same as twitching the knob back and forth randomly at high speed. Are you filtering...
  31. You can get distortion when adjusting the delay...

    You can get distortion when adjusting the delay because you are violating the Nyquist rate. It only occurs when changing the delay value?

    If so, this can happen because Nyquist sets a limit on how...
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    Thanks KurtE, I was not aware of that particular...

    Thanks KurtE, I was not aware of that particular transfer() function, I'll go look into it. As for the the cache issue, should not the pointers to the buffers be volatile? In fact, shouldn't this be...
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    @KurtE You're pretty knowledgeable about SPI and...

    @KurtE You're pretty knowledgeable about SPI and DMA. I think you also worked on the T4 beta? What do you think are the odds of us getting SPI DMA support built right in the teensyduino libraries (as...
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    Luckily, it can be changed on the fly! To explain...

    Luckily, it can be changed on the fly! To explain a little, the output driver (PAD register) settings are done on a per-pin basis rather than 'function' basis. Each pin can be configured for several...
  35. Be aware the 45 MHz parts have a dummy cycle...

    Be aware the 45 MHz parts have a dummy cycle between the address and the data. The 20Mhz parts don't have that
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    @DD4WH: The assignments can likely go anywhere...

    @DD4WH: The assignments can likely go anywhere after you've called Wire.begin() for I2C, during my testing I had them at the end of setup(). The I2S stuff starts up as soon as the I2S object is...
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    In general this is true. But you also need to...

    In general this is true. But you also need to consider PCB routing. Tracks with fast edges can couple into adjacent tracks where then run close and parallel. Thus, data lines that run right next to...
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    Hey Paul or anyone from the Beta who worked on...

    Hey Paul or anyone from the Beta who worked on I2C/I2S, question about this resistor. At first, I couldn't get my T4 working with my WM8731. As we already know, the WM8731 is sensitive to overly fast...
  39. There's actually a new 4Mbit SPI now so no need...

    There's actually a new 4Mbit SPI now so no need for FRAM if that's enough capacity. Check out ISSI IS62WVS5128
  40. Will it work? Yes and no. #1) They require a...

    Will it work? Yes and no.

    #1) They require a bit of startup work. You must hold SCLK low and CS# high during power on sequence, then issues a couple custom commands to reset the device. Not a big...
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    In this algorithm you are not using the same...

    In this algorithm you are not using the same values over and over again so they can't be precomputed like for wave synthesis. You are taking the input complex phasor and multiplying in by another...
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    I was working on a pitch shifter for the T3.6...

    I was working on a pitch shifter for the T3.6 that implements the Ocean's pitch shifting algorithm. It is a spin on the concept of the phase vocoder. The basic process is

    1) Use overlapping STFT...
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    Thanks Paul. Very much looking forward to using...

    Thanks Paul. Very much looking forward to using the Teensy 4.0 with my TGA Pro and this info will help me make an adaptor board. I presume the 100 ohm resistor on MCLK was to help absorb some...
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    Teensy 4.0 I2S Support

    I understand that the T4 is not direct pin compatible with the audio shield as the I2S pins are in different locations. Looking through the massive Beta thread, there was some discussion about an...
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    Assuming the SSOP part, Pin 22 (CSB) of the...

    Assuming the SSOP part, Pin 22 (CSB) of the WM8731 controls the I2C address. Pin 21 (MODE) controls whether it is I2C or SPI control interface. For two WM8731s, pull or tie the MODE pin low on both...
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    Kicad is great

    Kicad is great
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    Yes, use a sine wave. When I made my chorus I got...

    Yes, use a sine wave. When I made my chorus I got it working glitch free with a sinewave first, then moved on to investigating ways of bandlimiting the other waveforms like triangle.
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    Don't worry! We're hear to help. You might...

    Don't worry! We're hear to help.

    You might also want to try something dead simple first. Rather than designing a proper BiQuad IIR filter, what about just a 1st order IIR where you have



    //...
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    You can't use a raw triangle wave as a modulation...

    You can't use a raw triangle wave as a modulation source directly, it will cause glitching because a perfect triangle has infinite bandwidth due to discontinuities at the peaks/troughs. This infinite...
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    Earlier this year I was working on a chorus for...

    Earlier this year I was working on a chorus for my BALibrary. In order to get the chorus sounding right with no glitches, I had to do exactly what Chip says here. You cannot use a static delay value...
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