Re: Proof of concept: soundcard as console device

Quoting Poul-Henning Kamp <phk@xxxxxxxxxxxxxx> (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
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