Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!ukc!mucs!select4!david
From: david@select4.uucp (David Tait)
Newsgroups: sci.electronics
Subject: What interface do LCDs use?
Summary: I bought an LCD and don't know how it works.
Message-ID: <6499@ux.cs.man.ac.uk>
Date: 18 Sep 89 19:45:10 GMT
Sender: news@ux.cs.man.ac.uk
Reply-To: tait@v1.ee.man.ac.uk
Organization: University of Manchester, UK
Lines: 43

Hi all,

I recently bought a liquid-crystal display (LCD) module from a local
electronics junk shop for no better reason than it was cheap, looked
useful and I thought I might learn something about this technology.  The
display is made by Toshiba (model ZQ8045D-101, circa 1986 I'd guess), and
the display area measures 100mm by 275mm.  Unfortunately, there were no
details available, hence the low price.  I might be able to get some
info from Toshiba, but I don't know whether it's an OEM product or only
used in their own micros.  I thought I'd ask the net if anyone knew
anything about such things.

The PCB is littered with surface mount chips (display drivers with
names like M5279 and M5278, a few standards like '244, '390, '163 etc,
and an LA5316, whose function is a mystery).  Connections to the module
are via a 20-way edge connector, and after some scrutiny of the tracks
leading to pins 16 and 8 of the standard chips, plus checking the polarity
of electrolytics connected to the LA5316, I connected a 5V supply (I think
a -5V supply is also used, but I grounded this pin).  Anyway, I was
rewarded by a randomly changing display (vertical bars mostly) when I
touched some of the unconnected edge connector pins.  The display
appears to have 200 rows of 640 pixels (a very useful size).

Discounting power and ground tracks, there seem to be a total of
11 pins which need to be connected (one of these seems to blank the
display).  Just what kind of interface is this?  there are too many pins
if it used serial data with X and Y clocks, and too few pins if it had
direct addressing of X and Y.  My best guess is that it uses a raster mode
with X and Y clocks, X and Y resets (horizontal and vertical sync) and
serial data taken in 4-bit chunks.

I would be very interested to hear from anybody who knows anything about
this module, but I would also welcome general comments about the typical
method of interfacing similar LCD systems.

Thanks for taking the time to read this.

Best wishes, David.
---
David Tait,                   Tel/Fax:   +44-61-275 4504/4512
Electrical Engineering Dept,    JANET:   tait@uk.ac.man.ee.v1
The University,                  UUCP:   ...!mcvax!ukc!muee!tait
Manchester,  M13 9PL,  UK.       AX25:   G0JVY @ GB7NWP