Looking a the source you mentioned, the time delays there are based on
4MHZ
clock. If you're going faster, the delays will need to be adjusted.

I recently used an optrex 16X2 in place of another brand for a circuit I
built.
While they both were "compatible" as far as data exchanged, the pins
were not
in the same order. I had to be real careful to cross reference from the
original
drawing to make it match the optrex pinout.

Mine didn't work the first time either. For me, the problem was no more
than
just playing with the contrast though.( I felt REAL smart after that
one)

If you'd like to try another version of PIC source to drive your
display, grab
www.diversifiedengineering.net/Files/CanEd_sourceco.zip

The 4 bit LCD routines are in an include file there. I'm running them
now on a
16F874 with no troubles at all.

side note: I'm now building a second unit, using a VFD instead of LCD
for the display.
The VFD interface looks like SPI, but there's no CS input, and the SPI
is already being
used by a few other things in this circuit. I'm taking a shot at
Bit-Banging the interface for the new display.

-----Original Message-----
From: Ashraf Farrag [mailto:afarrag@NC.RR.COM]
Sent: Tuesday, May 07, 2002 10:44 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]: Help with Optrex 16x2 LCD display


Greetings,

I'm new to this list and was wondering if someone could assist me in
determining if I've done
something "really, really, bad (tm)" to the Optrex LCD 16x2 display I'm
trying to interface to a Microchip 16F876.

I hooked it up according to the datasheet, and ever since the first time
it
has been powered on, the first line goes all black
(all solid / non-blinking cursor characters).  Adjusting the contrast
yields
a lighter/darker all black first line.  The second line isn't on, ever.

Any and all attempts to get it to initialize have failed.  I've tried
the
auto-init with a delayed power-on (using a RC circuit).
I've tried initialization using my own code in 4-bit mode, which I've
stepped through a line at time with the ICD, and watched the pins go
high/low with a voltmeter appropriately as I stepped through the code
with
the ICD.  Everything SEEMS to be correct (as in, each line of the
supplied
specs for initialization is sent), but alas, I know something is wrong.
The
question is what? :-(

Finally, I wired it up for 8-bit mode, and used Tony Nixon's '877
program,
only making changes so that it used PORTC and PORTB instead of PORTD
http://www.piclist.com/techref/microchip/16F877/tlcd.asm
(as in, my changes were minor enough, that I'm sure it didn't affect the
program's functionality)

What does an Optrex display (or one with a Hitachi LCD driver) do
normally
when powered up?
Should I expect a blank display?  There is nothing on Optrex's website
about
this...

Thanks,
Ashraf Farrag

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