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To: freebsd@sopwith.solgatos.com
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Tue, 02 Jan 2007 12:40:44 GMT."
	<200701022040.UAA03200@sopwith.solgatos.com> 
Date: Tue, 02 Jan 2007 21:35:00 +0000
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Cc: freebsd-hardware@freebsd.org
Subject: Re: max UART speed? 
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In message <200701022040.UAA03200@sopwith.solgatos.com>, Dieter writes:
>http://en.wikipedia.org/wiki/UART
>
>lists UART speeds up to 2,764,800 bits/second.
>
>Does it take a special magic UART to do this?
>
>termios.h only goes up to 921,600

There is no theoretical upper limit, only signal integrity problems.

Regular chips can only go to 115200 because of the input clock
frequency they have to work with.

If you run them on 8x normal clock, you get 921600, 2764800 is
24x normal clock.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.