From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1NVH2N-0006UH-50 for garchives@archives.gentoo.org; Thu, 14 Jan 2010 04:10:23 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 816A6E0B5F; Thu, 14 Jan 2010 04:09:51 +0000 (UTC) Received: from mail.osagesoftware.com (osagesoftware.com [216.144.204.42]) by pigeon.gentoo.org (Postfix) with ESMTP id 4F22EE0B5F for ; Thu, 14 Jan 2010 04:09:51 +0000 (UTC) Received: from osage.osagesoftware.com (osage.osagesoftware.com [192.168.1.10]) by mail.osagesoftware.com (Postfix) with ESMTP id BFCF87BC52 for ; Wed, 13 Jan 2010 23:09:50 -0500 (EST) Date: Wed, 13 Jan 2010 23:09:50 -0500 From: David Relson To: gentoo-embedded@lists.gentoo.org Subject: Re: [gentoo-embedded] serial port handling question Message-ID: <20100113230950.7feb6342@osage.osagesoftware.com> In-Reply-To: <20100114034753.15128.qmail@stuge.se> References: <20100113185240.4bc9d721@osage.osagesoftware.com> <27dfa3d1001131856u29a0b5e0s82001c90956b27c@mail.gmail.com> <20100114034753.15128.qmail@stuge.se> Organization: Osage Software Systems, Inc. X-Mailer: Claws Mail 3.7.3 (GTK+ 2.16.6; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-embedded@lists.gentoo.org Reply-to: gentoo-embedded@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Archives-Salt: cd5cf5e0-d025-49cf-a42b-f594853edf12 X-Archives-Hash: cf643df7c9bbf0a696e7b6c9cafce857 On Thu, 14 Jan 2010 04:47:53 +0100 Peter Stuge wrote: > Daniel Stonier wrote: > > there's a setting in the termios options structure for rts - have > > you tried that? > > > > 'man termios' - look for CRTSCTS. > > Note that this flag does not directly control RTS, but rather it > instructs the kernel whether RTS/CTS signalling should be used for > flow control or not. > > As David noticed, there is no API for directly controlling RTS in > Linux, it can only be done by the serial driver itself or a line > discipline driver. > > > //Peter Hello Peter and Daniel, Information greatly appreciated. I'll digest it tomorrow when I'm more alert. After bashing my head against the wall (including experimentation with CRTSCTS), I spent a while reading drivers/serial/8250.c and found that CRTSCTS used only for enabling AFE (automatic flowcontrol enabled). Not having adequate specs for the protocol or hardware involved, there's some mystery as to exactly why RTS is used as it is. For certain, it'll be interesting tomorrow to learn more of termios and line discipline drivers (a new term for me). Ciao, David