Date: Wed, 27 May 1998 15:00:50 -0400 (EDT) From: Peter Dufault <dufault@hda.com> To: marc@hippocampus.net (Marc Nicholas) Cc: small@FreeBSD.ORG Subject: Re: LCDs... Message-ID: <199805271900.PAA18304@hda.hda.com> In-Reply-To: <Pine.BSF.3.95.980527150713.19209J-100000@neuron.hippocampus.net> from Marc Nicholas at "May 27, 98 03:09:50 pm"
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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? 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. > > <dumb question> 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
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