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1

Hi !

I need to have a board developed with 22 audio channels, or 11 stereo
sound cards.

There are 2 options:

1) Redevelop the board to add those sound cards to it. (instead of 1
card as it is presently on the board)
2) Develop a separate board that will have a USB repeater on it and
those 11 sound cards all on one board.

They do not have to be able to play at the same time. If the system
will be able to play 8 mono channels at the same time, that would be
sufficient.

Not sure what the volume is of the existing sound output, I need 10W.
If the existing one is less I will need an amplifier.

The final solution should be tested and working. Since the drivers for
the existing sound card already exist, and will just be multiplying
the number of sound devices, I assume there will be no need to write a
driver. But the OS will have to be loaded on the system and tested as
well.

Please contact me if you can be of help. Thank you !

2

Hi,

As I see it you only need 2 x 6port USB hubs to connected to 2 of the BB usb ports, although 1 hub with 11 or 12 ports may also exist.

Then you can connect 11 usb sound cards on the hubs.

Power is an issue, but you will have no problem if you are using good quality, powered usb hubs.

Stability of the linux driver though may be an issue which has to be investigated…

Hope this to be of some help to you.

Regards,

Markos

3

First, You need to do "proof of concept" to find out if the Beagleboard can provide such bandwidth on its USB bus.
And, you can also find out what software you need and if they can do the job.
So, get 11 sets of USB stereo sound adapter and Class-T digital amplifier, and try them out.
You can get an idea of how do they look by the following URL:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=180-963
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=310-300

4

BB has very low bandwidth USB interface

5

You could use the McBSP3 on the extention board and add i.e. 4 8
channel codecs (32 channels at all). All you have to do is to do some
changes in Alsa ASoC (adding a second sound interface McBSP3 in
addition to McBSP2) and a codec drive (this can be very simple, i.e.
if you don't have analog mixer in the codecs.). So you end up with a
32 channel audio interface, you could split into 4x 8 sound card or
16x 2 channel sound cards with Alsa.

If have done this for 16 channels (I connected a FPGA to BB instead of
multiple codecs. The codecs are connected to the FPGA as well. But you
can connect them direct) and it's working pretty well.

USB bandwitdh is quite OK for an embedded processor. Using a Gigabit
ethernet interface I was able to transfer appr. 11-12 MBytes per
second. That is identical to 64 audio channels.

Thorsten