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    Project Cyborg Ears - wearable 'DSP hearing experience' platform

    And you're doing a great job at it, not to mention the new hardware you manage to put in our hands every year ;) The above comment of mine is a year old and represents the (yet unfulfilled) idea to make certain key elements (like the SGTL5000 control code) less dependent on fixed 16 bit 44.1kHz...
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    Project Cyborg Ears - wearable 'DSP hearing experience' platform

    @chipaudette: as the teensy's ARM chip is permanently handicapped in the 24-bit audio department as it's DSP instructions only work on 16 bit samples, audio library support for 24 bit is notoriously lacking, too. Consequently, there was the need for intensive low-level work on basic I2S and...
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    Update: the AVC issue is finally going to be addressed in Issue #209 and matching pull request #210.
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    Bit-bang multiple I2S inputs simultaneously

    Hello Manatok, have you had a look at our project description here in the forum? I think there are at least 3 issues at hand which complicate your project if you decide to go for I2S instead of 4 analog microphones: - lacking 24 bit microphone support (most I2S mics are 24 bit, the standard...
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    I've got to extend the report, things are somewhat worse: AVC_ATTACK and AVC_DECAY are also affected (code source). They need 12 bit, but also get cast to uint8_t: uint8_t att=(1-pow(10,-(attack/(20*44100))))*pow(2,19); uint8_t dec=(1-pow(10,-(decay/(20*44100))))*pow(2,23); Again, the...
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    Multiple Stereo Inputs on Teensy 3.1 with Audio Shield

    @jdbliesener: Is the analogSyncRead(...) implemented by the dual-ADC library not good enough? I see that they're just started sequentially, but if that means microsecond-level delay, it might be fine for audio. Should be testable by sampling a fast signal with both ADCs and looking for variations.
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    We've found an important library error: in the control_sgtl5000.cpp AudioControlSGTL5000::autoVolumeControl(..), the audio volume limiter value is bogus due to a wrong cast: uint8_t thresh=(pow(10,threshold/20)*0.636)*pow(2,15); while the formula is fine - besides minor rounding issues -...
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    Teensy as USB Headset Adapter

    I used the regular Serial.write(), which can also write several bytes via Serial.write(buf, len). USB Serial transfer is already highly optimized on the teensy. I don't have code for the regular audio library data transfer.
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    Multiple Stereo Inputs on Teensy 3.1 with Audio Shield

    @randomthumper: Your question about 2x stereo in on the teensy + audio shield platform is a good one. The teensy 3.1 DOES have two ADCs, and there is code support for it, look here. Now, what about 2x stereo? The easiest way will probably be to let the SGTL5000 chip on the audio board grab...
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    24 bit audio boards

    @whollender, @Paul: I'll try to go a bit more into detail about my reasons, as there seems to be some misunderstandings. I'm not an audio expert by trade, so some of my understanding of issues along the way may be flawed or rely too much on "the engineers knew why they were doing it". If you...
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    "high speed" data logging

    Side remark: when benchmarking "virtual serial" connections, the host-side software (realterm, screen, minicom ..) mostly isn't able to handle multi-megabaud-rates, or doesn't use the necessary settings. A good starting point for performance is the "Transmit Bandwidth Benchmark" code made by Paul.
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    24 bit audio boards

    @whollender: I guess that with codec you mean the PCM CODEC you are using on the "big" audio board? @WMXZ: the code looks simple, but I'm not sure how well it will work in our microphone-dependent application. We need a lot of digital amplification on the SGTL5000 to get their audio volume to...
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    Teensy as USB Headset Adapter

    @TronicLabs: I can definitely confirm by experiments that there is enough bandwidth available for a stereo 24-bit 48kHz audio stream. (tested from the teensy to a computer with real sound, but sent via USB-Serial, which is far from optimal in terms of usability). Teensy USB is based on USB 1.1...
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    @Paul: The first pull request is online. Regarding a more fine-tunable enable() function for the SGTL5000, I'm thinking about which CHIP_CLK_CTRL and CHIP_I2S_CTRL settings to expose: SYS_FS, SCLKFREQ and DLEN are a must for 24-bit MS is necessary to put the SGTL5000 into I2S master (might be...
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    24 bit audio boards

    @WMXZ, whollender: we're another group running a teensy 24 bit audio (project description: see here) and very interested in anything you can cook up in that direction. @WMXZ: do you have sample code for this available? My impression was that "just copying 16 bits" was not enough and e.g. at...
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    Hello Paul, I'll send you a pull request soon that addresses some of the issues. I was aware of the GUI and the "helping information" there, but I didn't realize that the documentation for the audio functions would be maintained on an external page instead of in the code itself, so I never took...
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    [Audio library] control_SGTL5000.cpp documentation / improvements

    For our Audio project presented in this thread, we've been using the SGTL5000 hardware abstraction class control_sgtl5000.cpp (part of the audio library created by Paul). We've found several minor and a few major things that could be improved. Lacking/misleading function documentation: GEQ...
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    Project Cyborg Ears - wearable 'DSP hearing experience' platform

    Exciting news: I've just realized that I was wrong about the claimed inability to mix ADC (=LINE-IN) with the main I2S_IN audio. While the audio switch in general is just a simple switch as mentioned, the SGTL5000 makers have also included an component to the DAP (digital audio processor) that...
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    Project Cyborg Ears - wearable 'DSP hearing experience' platform

    @riodda: Yes, that is correct, the SGTL5000 is our 'only' means to manipulate the audio data in this signal flow configuration. Regarding mixing and 'real' DSP work: The SGTL DSP is limited to enhancing a single stereo audio stream with the audio blocks I've listed before, which don't provide...
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    Audio Adaptor - misleading schematic

    @Stendall: good catch, the "Typical Application Schematic" on page 59 of the SGTL5000 datasheet agrees. On a (very) quick look, the actual board layout looks correct in this regard, by the way, so it may only be a documentation error.
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    Audio Adaptor - misleading schematic

    Hello all / Paul, as with every "serial" connection that is labeled RX or TX, there is a tendency to confuse who is actually receiving or transmitting the data. In case of the teensy audio adaptor, this is also the case for the I2S RX/TX pins. This RX/TX situation is easy to get from the...
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    Audio Adaptor REV B - missing documentation

    Hello all / Paul, we are working with several teensy audio boards and realized that most of those are actually a new hardware revision REV B, for which there is no explicit documentation yet. The apparent changes to the board itself are fairly minor: two resistors in series between pin 10 and...
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    Project Cyborg Ears - wearable 'DSP hearing experience' platform

    Hello all, We would like to present you an extensive audio hardware project that we are currently working on, and some of the new ground we've explored relating to teensy audio capabilities. Our goal We aim to augment 'normal' human hearing with digitally processed realtime audio recordings...
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