[AudioI] OCTO soundcard DC input (+ some output measurements)

[Staš Vrenko]

Hey,

I'm working on a project in which I'll use the Octo soundcard for
capturing, processing, and outputting DC voltages.

Using PD (Pure Data) for signal generation and a digital o-scope for
measurement, me and my colleague managed to output DC voltages (directly
from positive pins, not using breakout RCA boards) of approx. 0.77V
(@amplitude of -1), 2.44V(@ 0) and 4.2V(@ +1). The negative pins output an
inverted signal (same p-p though).

The DC INPUT testing (not using breakout RCAs) was a bit confusing.

There's a channel number re-assignment problem when Pure Data gets opened
and closed or when RPi gets rebooted. I've read it can be related to a
driver problem?

Getting the AC signals into PD was easy but there was no such luck with DC
- so I'm
wondering whether DC capturing has been tested/proven to work?
If it has - could it be that there's a DC filter somewhere in RPi signal
path (JACK, etc.)?

Otherwise, it's a great card & hats down for developing a custom IC!

Thank you for your answer, best,
Staš :)
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