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 1NVDyq-0001gp-4G for garchives@archives.gentoo.org; Thu, 14 Jan 2010 00:54:32 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id B834AE1224 for ; Thu, 14 Jan 2010 00:54:31 +0000 (UTC) Received: from mail.osagesoftware.com (osagesoftware.com [216.144.204.42]) by pigeon.gentoo.org (Postfix) with ESMTP id 6A3C6E07F5 for ; Wed, 13 Jan 2010 23:52:41 +0000 (UTC) Received: from osage.osagesoftware.com (osage.osagesoftware.com [192.168.1.10]) by mail.osagesoftware.com (Postfix) with ESMTP id F0F5A7BC35 for ; Wed, 13 Jan 2010 18:52:40 -0500 (EST) Date: Wed, 13 Jan 2010 18:52:40 -0500 From: David Relson To: gentoo-embedded@lists.gentoo.org Subject: [gentoo-embedded] serial port handling question Message-ID: <20100113185240.4bc9d721@osage.osagesoftware.com> 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: 0cbaa2a5-1566-4490-a8e0-2e516335b82e X-Archives-Hash: b704b36ea5173d6c486a5527f35c6fcc G'day, I'm porting some old DOS code to Linux for a medical device that is being upgraded. Among other goodies, it has a sensor that sends data at 115KB to an onboard NS16550A (or equivalent). The sensor is controlled (in part) by setting RTS on and off. I looked high and low (pun intended) for an ioctl or similar call that would allow this level of control and couldn't find anything. I finally ended up using the ollowing lines of code: outb(inportb(MCR) | 0x02, MCR); //DTR,RTS=ON outb(inportb(MCR) & ~0x02, MCR); //DTR=ON,RTS=OFF Directly tweaking the I/O port runs against the grain, but it's the only thing I've found that works. Is there a better way to control the chip? Regards, David