[alsa-devel] Enabling SPDIF output on Turtle Beach Audio Advantage Micro (CMEDIA CM102S)

Eric Sandeen sandeen at sandeen.net
Wed Mar 28 16:30:57 CEST 2007

I have this Turtle Beach Audio Advantage Micro usb sound card, er, 
stick.  Inside it has pretty much nothing but a C-Media CM102S chip.  TB 
claims, as does C-Media, that it can do S/PDIF out, and I believe them 
based on the glowing red TOSLINK light.  :)

I found previous emails on this list 
suggesting that there is probably some magic to be applied to tell usb 
hardware to go into S/PDIF mode.

I've captured some traces under windows, linked from 

Specifically, http://sandeen.net/tbaam/2spkr-spdif.txt seems to be a 
fairly short burst of USB activity when I used the control panel to 
switch from 2 speaker mode to spdif mode.  I see the exact same activity 
when switching from headphone mode to spdif mode.  Strangely, switching 
from, say, spdif back to 2 speaker seems to generate a lot more traffic.
The full annotated trace is here: http://sandeen.net/tbaam/usbsnoop1.txt

In any case, are these traces helpful to anyone who understands how to 
talk to a C-Media CM102S usb sound card?  Does it look possible to poke 
this hardware into S/PDIF mode with this information?



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