Mulitchannel Audio project advice...

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Joined: Fri Aug 10, 2018 9:48 pm

Mulitchannel Audio project advice...

Postby pryankster » Fri Aug 10, 2018 10:54 pm

I'm designing a device (Drum sequencer) and I'm looking at using the XCore processor to handle the audio portion. The main "cpu" portion of the system (user interface, housekeeping, mass-storage of samples, etc.) will be run by a Raspberry PI Compute module.

The problem I have is that in addition to 8 channel analog audio output, I want the device to also connect to an upstream Digital Audio Workstation (DAW -- Mac / PC, etc.) and appear as a USB Audio Class2 device.

Ideally, it would look something like this (pardon the ASCII graphics):

Code: Select all

+-----+ USB Audio2/MIDI+----------+ USB Audio2/MIDI +------+
| rPi |<=============> |   XCore  |<==============> | DAW  |
+-----+                +----------+                 +------+
                        vvvvvvvv|| Analog & SPDIF In/Out[/font]
If the XCore processor is running as a USB device for the DAW, is there another way for the RPi to send audio to the XCore? (SPI? SDIO?)

One option is to put another "cheaper" audio chip and connect it to the XCore to have it handle the upstream-to-DAW USB, but I'd rather not have the additional BOM cost.

Any suggestions would be very helpful.
-- pryankster
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Postby infiniteimprobability » Thu Aug 23, 2018 9:04 am

It is theoretically possible to have dual hosts but the standard reference design is hard coded to have a single USB host.
Are you planning to build many units? If so, it may be worth investing in the software effort to make USB multi-host capable (months probably) or it would be a lot quicker to simply lay down 2x XU216s each running a version of the same ref design, and connect them via I2S or TDM etc. Both could run asynch USB with the same local MCLK. You would need to fix the sample rate though..

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