The PIC16C923/924 can drive up to 116 segments when used with a 1:4 multiplexed LCD pannel. >From owner-piclist@mitvma.mit.edu Sun Jun 7 22:42:52 1998 >Received: from PEAR.EASE.LSOFT.COM (206.241.12.19) by vms.dc.lsoft.com (LSMTP for OpenVMS v1.1a) with SMTP id <4.5C812277@vms.dc.lsoft.com>; Mon, 8 Jun 1998 1:29:36 -0500 >Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV release 1.8c) with > NJE id 3959 for PICLIST@MITVMA.MIT.EDU; Mon, 8 Jun 1998 01:30:33 -0400 >Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail > V1.2b/1.8b) with BSMTP id 1963; Mon, 8 Jun 1998 01:30:08 -0400 >Received: from mail.eskimo.com (204.122.16.4) by mitvma.mit.edu (IBM VM SMTP > V2R3) with TCP; Mon, 08 Jun 98 01:30:06 EDT >Received: from eskimo.com (ape.ndip.eskimo.net [204.122.28.61]) by > mail.eskimo.com (8.8.8/8.8.8) with ESMTP id WAA25617 for > ; Sun, 7 Jun 1998 22:29:44 -0700 (PDT) >X-Mailer: Mozilla 4.04 [en] (Win95; U) >MIME-Version: 1.0 >References: > <357A1CD9.563D@blacksand.NS.com> >Content-Type: text/plain; charset=us-ascii >Content-Transfer-Encoding: 7bit >Message-ID: <357B76C9.DB25D6F3@eskimo.com> >Date: Sun, 7 Jun 1998 22:29:46 -0700 >Reply-To: ape@eskimo.com >Sender: pic microcontroller discussion list >From: Mark Devin Newland >Organization: Devin Electronics >Subject: Re: [OT] Voltage and Polarity of an LCD Display >To: PICLIST@MITVMA.MIT.EDU > >I also have a simular project that I am working which requires HH:MM:SS >in 24 hour format. Both of the replies that I have seen to your post refer >to the LCD driver PIC chip. If one works out the needed segments for a 6 >digit clock, 32 segments is not enough and have yet to find a 6 digit LCD >display that was multiplexed. Need about 36 segments. I have found quite >a few 32 bit LCD drivers which is not enough unless you want to cascade >two of them together. I did, however, come accoss something last week >that gives me hope. My 1992 Signetics I2C data book shows a 40 seg >driver. Part number is PCF8576. > >As far as the rest of your questions, just let the PCF8576 handle it for >you. Thats what it's there for. > >Michael Ghormley wrote: > >> I guess this is my night to post to the PICLIST! >> >> I have a clock project that needs to display hh:mm:ss on a largish LCD >> display. I have found a nice one at a good price (surplus -- no docs or >> markings of any kind) and got a sample to prototype. It is a bare (no >> driver chips) LCD in a kind of huge DIP. It would be perfect for my >> purposes. >> >> I sat down tonight to begin probing it for the pinouts when I realized >> that, while I have done any number of HD44780-based projects, I had no >> idea about driving a "raw" LCD. >> >> 1) What voltage range is typical? Is 5VDC sufficient? >> >> 2) What about polarity? Can these things be damaged by reverse >> polarity? >> >> 3) What about series resistance? I know these are *very* low amperage >> devices, but do I need a series resistor with each segment for some >> reason? If so, what size? >> >> 4) Is there going to be a chip-wide contrast pin on this thing, or is >> that up to the hardware that drives it? > ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com