Proof of concept: soundcard as console device

[Alexander Leidinger]

Quoting Poul-Henning Kamp <phk at phk.freebsd.dk> (from Fri, 31 Aug 2007  
09:42:51 +0000):

>
> Yesterday while I was futzing with my new laptop and ACPI suspend/resume,
> I once again found myself cursing the nutjob who took away our serial
> ports.

Lucky those people with a firewire interface...

> Then my mind wandered around a bit and suddenly it struck me: all
> modern hardware have built in AC97 sound hardware, and it offers a
> channel with a pretty decent bandwidth.

You are too late, Intel is moving to HDA and away of AC97. And it  
seems everyone except Creative is following (there are companies with  
their own interfaces (VIA envy24), but often they provide a HDA  
chipset too). Creative doesn't really matter, as they don't provide  
docs and everyone tries to avoid it.

> This morning I ran a simple experiment, from userland, but the
> result show clearly that the idea is workable.
>
> The transmission format I used: send a negative transient to start
> a character and after N samples, send a positive transient, where
> N is the ASCII value of the character + a small constant.

Some cards have digital-out/in (SPDIF), maybe it's an option for you.

Bye,
Alexander.

-- 
Never give an inch!

http://www.Leidinger.net    Alexander @ Leidinger.net: PGP ID = B0063FE7
http://www.FreeBSD.org       netchild @ FreeBSD.org  : PGP ID = 72077137