From owner-freebsd-small Wed May 27 12:25:02 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id MAA08834 for freebsd-small-outgoing; Wed, 27 May 1998 12:25:02 -0700 (PDT) (envelope-from owner-freebsd-small@FreeBSD.ORG) Received: from hda.hda.com (hda-bicnet.bicnet.net [208.220.66.37]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id MAA08796 for ; Wed, 27 May 1998 12:24:42 -0700 (PDT) (envelope-from dufault@hda.hda.com) Received: (from dufault@localhost) by hda.hda.com (8.8.5/8.8.5) id PAA18304; Wed, 27 May 1998 15:00:50 -0400 (EDT) From: Peter Dufault Message-Id: <199805271900.PAA18304@hda.hda.com> Subject: Re: LCDs... In-Reply-To: from Marc Nicholas at "May 27, 98 03:09:50 pm" To: marc@hippocampus.net (Marc Nicholas) Date: Wed, 27 May 1998 15:00:50 -0400 (EDT) Cc: small@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL25 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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. > > We use the I2C bus using the access.bus physical TELCO jack pinout > > for this because these LCDs and buttons eventually run on > > microcontrollers. I like this - it daisy chains well so you can > > have a button module and a display module and click them together. > > How do you get an I2C bus on a PeeCee? Can you fake it > somehow? You either brute force bit-bang through the parallel port with some hacked adapter to let you tie together the input and output bits, or you buy an expensive adapter that has nothing but a PAL and a Philip's controller chip. We used to use the parallel port but now use the controller board - this is for developing and prototyping the embedded applications and the cost for a few boards is not an issue. > I'd be interested in references for I2C buttons...or keypads. Basically they are home grown using what you'll find in the Philips data book - we use the parallel to serial converter chip to drive the Optrex LCD module on output (as you would from the parallel port) and discrete switches and a rotary encoder / push button on input, and the LED driver chip to drive LED displays. Peter -- Peter Dufault (dufault@hda.com) Realtime development, Machine control, HD Associates, Inc. Safety critical systems, Agency approval To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-small" in the body of the message