[LAU] open hw soundcard (was Re: status usb2 for sound)

Hans Wilmers hanswil at notam02.no
Wed Nov 11 06:25:36 EST 2009

I am using embedded linux on ARM processors in another project, and have
been looking for a simple solution for multichannel outputs for a while
(8 or more), although inputs also are interesting. I have implemented a
noisy soundcard based on UCB1400 for my hardware a while ago, and could
do some tests with that.

I could do parts of:

1) testing OSC on ARM/embedded Linux
   (Don't know whether I could test netjack - I have no experience with

2) test sending sound to/from the board
   (but restricted to 10mbit/s, at the moment)

5) add the preamp part - there are good examples for that in the
datasheets for some differential amplifiers

Actually, if we go for this together, I'd suggest using a gumstix board
for the tests, or something similar that is completely ready. This would
make it easier to split the project into hardware and software, and it
would enable others to buy off-the-shelf material, or run a
software-only solution.

/ Hans

> On Tue, 10 Nov 2009 12:34:14 +0100 (CET), Karl Hammar wrote
> Well start from the top:
> 1, test netjack and osc if they are things to use
>    (someone else has to come with the expertise for that)
> 2, the same with dummy audio values from the microcontroller to see
>    if its performance holds, I have an evaluation board that one
>    could do that on
> 3, the same add any ADC and an ext. preamp to get real sound
> 4, refine the ADC part to satisfaction
> 5, add preamp part
> 6, add power-over-ethernet so its just ONE cable
> 7a, start to miniturize, possible makeing it small enought to sit
>     directly on the mic,
>  or...
> 7b, add channels
> I could do steps 2, 3, possible 4, 6 and possible 7.
> Nice, don't you think so?
> And, since ethernet is driven through transformers we won't have any
> ground loops, etc. On the negative side is that ethernet cables are
> more stiff than microphone cables, they have the wrong color ... it
> woun't look that good, and they are not that durable, same with its
> connector, but there are industrial version ethernet connectors one
> could possible use with more suitable cables.
> Regards,
> /Karl
> -----------------------------------------------------------------------
> Karl Hammar                    Aspö Data               karl at aspodata.se
> Lilla Aspö 148                                                 Networks
> S-742 94 Östhammar          +46  173 140 57                   Computers
> Sweden                     +46  70 511 97 84                 Consulting
> -----------------------------------------------------------------------

Hans Wilmers
Nedre Gate 5
N-0551 Oslo Norway
tlf.: +47 22358065

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