From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Parkins Subject: Re: tcdrain / TCSBRK / wait_until_sent delay Date: Mon, 9 May 2005 09:01:18 +0100 Message-ID: <200505090901.25433.andyparkins@gmail.com> References: <200505051650.38471.andyparkins@gmail.com> <200505071035.55508.andyparkins@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart3243809.tLWhuL0xBB"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: Received: from [195.102.65.187] ([195.102.65.187]:60648 "EHLO 369run02s.360vision.com") by vger.kernel.org with ESMTP id S263074AbVEIIBd (ORCPT ); Mon, 9 May 2005 04:01:33 -0400 In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: rich+ml@lclogic.com Cc: linux-serial@vger.kernel.org --nextPart3243809.tLWhuL0xBB Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Saturday 2005 May 07 19:09, rich+ml@lclogic.com wrote: > > > Have you tried hardware flow control, "stty crtscts < /dev/ttyX"?.=20 > > > With CTS strapped high, RTS should follow THRE||TE. > > > > That's an interesting idea - CTS is currently set by the RS485 converter > > to indicate when it has successfully turned the buffer around. So it > > goes, RTS set high, wait for CTS, send... Is what you're suggesting th= at > > I cut this wire and hold CTS high externally? > > Oh no, in that case you don't need to do anything. The transaction you > described is exactly what happens automatically when crtscts is enabled. > > However if your uart doesn't actually support AFE then it will be done > by the driver and have the timing characteristics you see already. > > Hook up your scope, "stty crtscts < /dev/ttyX; echo test > /dev/ttyX" and > see what happens. Are you sure that RTSCTS flow control is what you think it is? These days = RTS=20 means "request to send to me" rather than "I request to send"; that allows= =20 RTS and CTS to be crossed over in null modem cables - and puts the flow=20 control in the receiver directly. Of course in my case the RS485 converter is abusing the RTS line for its ow= n=20 purposes, which is why I set -CRTSCTS. Regardless of all that, I tried it anyway with no joy :-) I'm coming to accept that what I'm after isn't possible. How likely is it= =20 that I could patch the serial_core kernel driver to do the RTS control for= =20 me? Am I going to end up in the same situation? Andy =2D-=20 Dr Andrew Parkins, M Eng (hons), AMIEE --nextPart3243809.tLWhuL0xBB Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQBCfxjVwQJ9gE9xL20RAnGsAKDh/UXqUluYRafWLaG5ZwQM8cnrcQCg25lw MGPF4gsEeMcsWlnntjtDsgU= =6Rev -----END PGP SIGNATURE----- --nextPart3243809.tLWhuL0xBB--