>
> Hi Tony,
>
> >  I am having trouble initializing my 2x8 optrex lcd w/hd44780a
> > controller
> > in 4 bit mode.I have tried everything I could glean from the FAQ's but
> > it just
> > does'nt shift to 4 bit mode and all subsequent writes cause the cursor
> > to move
> > two places.In the simulator the write routine 4 bit writes upper
> > nybble,lower
> > nybble with no extra loops and the character printed bears no relation
> > to the
> > one I was attempting.I am using bits <4..7>b for data & bits <1..3>b for
> > control
> > The rs & r/w bits are output with enable low then enable is toggled high
> > and the
> > 4 data bits are output then the enable bit is toggled low.
>
> You might have a look at the following I did in Pascal just
> to get an idea of the steps to take.  The plan is to write
> the reset to 8 bit mode comand to the display 3 times as
> recommended in the data sheets and then send the set to
> 4 bit mode command once.  All 4 of the above were single byte writes
> after the last one then you start to write nibble/nibble.
>

>
> Be sure you are waiting the required amount of time between instruction
> writes to the display.
>
>   I had trouble at first writing to displays in 4 bit mode and got
> results like you see.  After I checked my code I found I wasn't quite
> waiting long enough between writes.  Doubling the delays (for overkill)
> worked!  I also found that the delays mentioned in spec sheets are only
> approximate.  Increase yours and see if it helps.
>
> Dave
>
> At 02:08 PM 12/17/96 -0500, you wrote:
> >Hello
> > I am having trouble initializing my 2x8 optrex lcd w/hd44780a
> >controller
> >in 4 bit mode.I have tried everything I could glean from the FAQ's but
> ---------------------------------------------------------------------------
> ( DSchmidt Technologies, Ventura CA         http://www.rain.org/~dschmidt )
> ( Freq selectors for FME/FMX/FM25, DTMF decoders. Email @spam@dschmidtKILLspamrain.org )
> ---------------------------------------------------------------------------

>
> Tony,
>
> >I saw only millisecond delays in the spec sheet and in desperation
> >wrote delays loops several seconds long.nada
> > I suppose I must have damaged something?
> >        Thanks  Tony M.
>
> Before you dispair, commit hari-kari, or go out and buy another LCD, there
> are somethings that you can do:
>
> 1.  Check all your connections.  The first time I did an LCD Project (using
> Walt Bank's code), I got nothing (and then noticed that the R/W line was
> left floating...
>
> 2.  Make sure that what you are doing is pretty simple; ie just try to put
> "A" on the LCD.  Don't go for the full implementation right from the start.
>
> 3.  Look for documentation; I didn't have a lot of luck with the FAQs on the
> internet (a *lot* of problems/errors).  But, the Optrex Data Sheet from
> Digi-Key (around $3.00) is pretty accurate (I've only found one
> inconsistancy/error so far).  I've never been able to find a Hitatchi Data
> Sheet for the 44780 (even from the local Toronto Hitatchi office) - they
> seem to treat them like the family jewels.
>
> 4.  Even without anything valid, you should be able to turn up the contrast
> and see the dots of the characters become visible.  If you don't see this,
> look at your power and contrast connections.
>
> 5.  You can build a simple, manual controller using a dip switch (with
> pull-ups) and a single-shot (ie 74121) and figure out what's the problem
> pretty easily.
>
> I've been there; I'm convinced that LCDs are pretty easy to use, just a real
> bugger the first time.
>
> Good Luck,
>
> myke
>
> Today, the commercial sector is advancing computer and communication
> technology at a breakneck pace.  In 1992, optical fiber was being installed
> within the continental U.S. at rates approaching the speed of sound (if
> computed as total miles of fiber divided by the number of seconds in the