Date: Wed, 27 May 1998 13:17:52 -0700 From: Mike Smith <mike@smith.net.au> To: Marc Nicholas <marc@hippocampus.net> Cc: Peter Dufault <dufault@hda.com>, Julian Elischer <julian@whistle.com>, freebsd-small@FreeBSD.ORG Subject: Re: LCDs... Message-ID: <199805272017.NAA01651@dingo.cdrom.com> In-Reply-To: Your message of "Wed, 27 May 1998 15:09:50 EDT." <Pine.BSF.3.95.980527150713.19209J-100000@neuron.hippocampus.net>
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> > > You could also drive the parallel connection on Optrex style > > controllers through the parallel port. > > I would imagine this would become timing sensitive, no? Not really; most controllers are more than fast enough. See /usr/share/examples/ppi for an example using the ppi 'geek port' interface (in -current) talking to the Hitachi LCD controller. You could backport this to 2.2 pretty trivially if you're willing to use the /dev/io hack. (I'm available to extend/customise this code at very reasonable rates. 8) > > 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. > > <dumb question> How do you get an I2C bus on a PeeCee? Can you fake it > somehow? There are serial:I2C adapters I believe, and I2C UART-like devices. > I'd be interested in references for I2C buttons...or keypads. I don't have any handy, sorry, but I do recall some pushbuttons with small LCDs in the button that IIRC used I2C for comms. > > Check the back of the mag "Circuit Cellar INK The Computer Applications > > Journal" (circuitcellar.com) for some RS232 displays I know absolutely > > nothing about (www.matrix-orbital.com). > > The Matrix Orbital stuff does indeed look neat, although a little > expensive for our application. Far too expensive, and more or less unnecessary for lots of applications. They take an ordinary parallel-interface display and put another board containing a micro on the back. Cheaper to do the work yourself. -- \\ 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
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