EEG trigger - technical question

[Bastian Epp <bepp@xxxxxxxxxxxxxx>]

Hi everyone!

I have a rather specific and technical question - before starting to 
develop something from scratch:

Is there a commercially available solution to translate a digital audio 
signal (preferrably from an ADAT channel, otherwise SPDIF) into parallel 
TTL (ie "printer port")? I am looking for something (let's call it "THE 
BOX") that does not require too much overhead in terms of devices.

Some background information:
We want to send our EEG trigger as a digital number on the sound card in 
one channel, along with two channels containing the stimulus. So "THE 
BOX" needs to decode the digital signal/number and encodes it onto 0/5V 
on a d-sub connector - without jitter!

We do have a box that does it with SPDIF, but I wonder if that is 
possible with ADAT directly? Looking into audio forums, it seems doable, 
I just couldn't find someone that actually did it. And as I said - 
before digging into digital electronics...it looks like a fun project 
though.

Any pointers welcome and (of course) I would be willing to share a 
concise summary if there is interest.

Thanks in advance and a wonderful day to everyone from sunny Copenhagen!

BAstian