From owner-freebsd-small Wed May 27 14:37:04 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id OAA07571 for freebsd-small-outgoing; Wed, 27 May 1998 14:37:04 -0700 (PDT) (envelope-from owner-freebsd-small@FreeBSD.ORG) Received: from dingo.cdrom.com (dingo.cdrom.com [204.216.28.145]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id OAA07254 for ; Wed, 27 May 1998 14:35:28 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (localhost [127.0.0.1]) by dingo.cdrom.com (8.8.8/8.8.5) with ESMTP id NAA01723; Wed, 27 May 1998 13:29:32 -0700 (PDT) Message-Id: <199805272029.NAA01723@dingo.cdrom.com> X-Mailer: exmh version 2.0zeta 7/24/97 To: Peter Dufault cc: marc@hippocampus.net (Marc Nicholas), small@FreeBSD.ORG Subject: Re: LCDs... In-reply-to: Your message of "Wed, 27 May 1998 15:00:50 EDT." <199805271900.PAA18304@hda.hda.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 27 May 1998 13:29:32 -0700 From: Mike Smith Sender: owner-freebsd-small@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > > You could also drive the parallel connection on Optrex style > > > controllers through the parallel port. > > > > I would imagine this would become timing sensitive, no? > > Check Mike's code which I didn't know about. I assume there > is a minimum setup time before you twiddle a handshake - I've > done this way back and don't remember there being any problems. Yes, there are assorted weird timing constraints. The Hitachi part dominates the 1-4 line alphanumeric LCD market, and datasheets for it are available in many places across the web. As a general rule, the constraints are command-based rather than handshake-based; you would need to be talking to the LCD memory-mapped off a fairly fast micro before you ran into problems. I doubt that you can coax a parallel port into going nearly fast enough to give it any trouble. > > I'd be interested in references for I2C buttons...or keypads. If you're doing this on a product basis, you're almost certainly better off DIY with a PIC or Z8 micro and a serial interface. Buying someone else's I2C keyboard/display combo is fine for one-offs, but the pricing I've seen would indicate that you'd be wasting far too much money on it. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-small" in the body of the message