From: David Woodhouse <dwmw2@infradead.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Chris Fowler <cfowler@outpostsentinel.com>,
Robert White <rwhite@casabyte.com>, Ed Vance <EdV@macrolink.com>,
'Linux PPP' <linuxppp@indiainfo.com>,
linux-serial@vger.kernel.org,
'linux-kernel' <linux-kernel@vger.kernel.org>
Subject: RE: RS485 communication
Date: 16 Mar 2003 10:05:31 +0000 [thread overview]
Message-ID: <1047809131.22070.33.camel@imladris.demon.co.uk> (raw)
In-Reply-To: <1047776160.1327.0.camel@irongate.swansea.linux.org.uk>
On Sun, 2003-03-16 at 00:56, Alan Cox wrote:
> RS485 supports CDMA, thats more than enough to implement ppp nicely, all
> you have to do is a little abuse in the app or driver layer to block
> sending when carrier is asserted
Note you don't need any separate lines for this. If someone else is
transmitting a zero while you are also transmitting a zero, that's fine
and you didn't stomp on each other. If someone else is transmitting a
zero while you are transmitting a one, you won and a one was
transmitted, and they back off. If they transmit a one while you
transmit a zero, then they won :)
That's how CAN does it, IIRC. I don't believe it actually requires
synchronous clocks.
--
dwmw2
next prev parent reply other threads:[~2003-03-16 10:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-13 16:56 RS485 communicatio Ed Vance
2003-03-13 17:46 ` Richard B. Johnson
2003-03-13 22:54 ` RS485 communication Robert White
2003-03-13 23:30 ` Chris Fowler
2003-03-15 8:07 ` Robert White
2003-03-15 15:42 ` Chris Fowler
2003-03-15 12:46 ` David Woodhouse
2003-03-16 0:56 ` Alan Cox
2003-03-16 10:05 ` David Woodhouse [this message]
2003-03-16 10:35 ` Russell King
2003-03-16 10:51 ` David Woodhouse
2003-03-16 18:23 ` Gerald Emig
2003-03-15 19:46 ` RS485 communicatio Pavel Machek
2003-03-16 19:57 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2003-03-17 5:41 RS485 communication Cigol C
2003-03-20 23:09 ` Robert White
2003-03-20 23:17 ` Chris Fowler
2003-03-21 2:48 ` Robert White
2003-03-24 11:43 Cigol C
2003-03-25 3:23 ` Paul Mackerras
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