From: Matthias Fuchs <mfuchs@ma-fu.de>
To: Christian Magnusson <mag@mag.cx>
Cc: linux-serial@vger.kernel.org
Subject: Re: Auto RS485 half-duplex control
Date: Sun, 24 Jan 2010 17:06:36 +0100 [thread overview]
Message-ID: <201001241706.37479.mfuchs@ma-fu.de> (raw)
In-Reply-To: <001801ca8c76$d7654bd0$862fe370$@cx>
Christian,
>
> I have searched in the lists for some kernel support to control the RTS-pin
> while sending characters to through an external RS232->RS485 adapter.
> The RS485 device I’m writing to, respond with an answer within approximately
> 2ms after my last sent character, and therefore I need to release the
> RTS-pin before that.
> If not, the returning characters will be unreadable due to the
> send-collision.
>
> Will this feature be implemented in the i386 arch (as it is for chris), or
> is there any reason to never include it in the future?
>
manually controlling the RTS (or any other pin) pin for RS485 duplex
control has been discussed here several time. Because it is not possible
to guarantee the correct timing in any situation this was always nack'd.
The only chance you have is to use a proper UART that is capable to do this
by hardware (e.g. some Exar UARTs or some UARTs that can be found on some
SoCs that are used in the embedded world).
Matthias
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prev parent reply other threads:[~2010-01-24 16:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-03 13:15 Auto RS485 half-duplex control Christian Magnusson
2010-01-24 16:06 ` Matthias Fuchs [this message]
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