xcore-200 board possible to bring up as separate audio devices?

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xcore-200 board possible to bring up as separate audio devices?

Post by Kirill »

Runnign Linux (Debian 9), I have an xcore-200 multichannel audio board that comes up as a single audio device of 10 channels (not sure why 10, expected 8). Is it possible to have it recognized as 2 or 4 separate devices of 2 channels each?
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Post by akp »

A thought I would have is to specify the descriptor as USB composite device of multiple USB audio class 2 devices. That should possibly work to show up as separate cards, but don't know for sure. I haven't done it. However, you would probably run into problems with the USB endpoint code because for sure you would need different endpoints for each virtual card (as the composite device needs different endpoints for each virtual card). And then you would probably need a single fixed sample rate (e.g. fixed 48ksps as only option) because having multiple sample rates will not work if you use a single I2S master clock (which the MC audio board only has a single I2S master clock). Obviously you would need separate buffers for each virtual card and somehow join them at the I2S/TDM level... and I am not sure if you could do all this without changing the number of cores in use. Seems non-trivial but perhaps someone has done it. Good luck!