d3e1bc8b59
The sample illustates how to achieve bidirectional asynchronous audio. Implicit feedback is the only way to achieve asynchronous USB headset on devices that have only one isochronous IN and one isochronous OUT endpoint. The sample implements stereo playback and mono recording. While it would be possible to have stereo recording, the commonly available headsets are mono only. The number of channels can differ between audio sink and source because the only requirement is that the two run on same clock. Signed-off-by: Tomasz Moń <tomasz.mon@nordicsemi.no>
42 lines
1.4 KiB
ReStructuredText
42 lines
1.4 KiB
ReStructuredText
.. zephyr:code-sample:: uac2-implicit-feedback
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:name: USB Audio asynchronous implicit feedback sample
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:relevant-api: usbd_api uac2_device i2s_interface
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USB Audio 2 implicit feedback sample playing stereo and recording mono audio
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on I2S interface.
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Overview
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********
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This sample demonstrates how to implement USB asynchronous bidirectional audio
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with implicit feedback. The host adjusts number of stereo samples sent for
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headphones playback based on the number of mono microphone samples received.
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Requirements
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************
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Target must be able to measure I2S block start (i.e. first sample from output
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buffer gets out) relative to USB SOF. The relative offset must be reported with
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single sample accuracy.
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This sample has been tested on :ref:`nrf5340dk_nrf5340`. While for actual audio
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experience it is necessary to connect external I2S ADC and I2S DAC, simple echo
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can be accomplished by shorting I2S data output with I2S data input.
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Theoretically it should be possible to obtain the timing information based on
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I2S and USB interrupts, but currently neither subsystem currently provides
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necessary timestamp information.
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Building and Running
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********************
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The code can be found in :zephyr_file:`samples/subsys/usb/uac2_implicit_feedback`.
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To build and flash the application:
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.. zephyr-app-commands::
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:zephyr-app: samples/subsys/usb/uac2_implicit_feedback
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:board: nrf5340dk/nrf5340/cpuapp
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:goals: build flash
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:compact:
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