On 10/7/21 6:17 am, Ian Crawford via People wrote:
Hi.  I'm helping a group of young people (age 10+) build a project around the Octo + R.Pi 4.

We have a dead output channel (6) at the Octo card:
https://github.com/Audio-Injector/Octo/issues/45
... and not sure what to do about it.

We want to replace the everything-to-all-channels config with one that allows us to play at least 4 independent channels.


That will work. As discussed, try to start jackd once after booting and keep it running.



We would like to know things like impedances, input + output voltage ranges, driver rate limits, whether the outputs are balanced or ground-bonded.


Outputs are balanced but the RCA connector is single ended. Impedances from the soundcard are as listed in the manufacturer page of the codec : https://master-nq.webp2.cirrus.com/products/cs42448/




We have no board layout, connection diagrams, programming manual or data sheet.


Here is an example connection to the soundcard - they are the RCA breakout boards which ship with the product :

https://github.com/Audio-Injector/AudioInjector.Octo.RCA/blob/master/AudioInjector.Octo.RCA.sch.pdf

You can design your own too !

Programming is just regular Linux kernel audio - ALSA for example, jackd, etc etc.



The Linux audio documentation is ... chaotic and assumes a high level of prior knowledge.

That is true - we will try to answer your questions.


We have no way of contacting the manufacturer, as far as we can see.


I am glad we finally have contact - thanks for ringing me earlier today.





    
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