Eric van Es wrote:
>
> Mike Keitz wrote:
>
> > There are 2 types of 16x1 modules out there.  One type has the
> HD44780
> >
> > chip and an LCD driver chip.  It uses x8 or x11 drive for a true
> > 16-character by one line.  The characters appear sequentially in
> RAM.
>
> > The other type has only the HD44780 chip.  The controller must be
> set
> > for
> > x16 drive, since it is logically an 8x2 display.  The LCD panel is
> > built
> > so the 2 lines appear end to end rather than above each other.
> There
> > is
> > a gap in the RAM between the two sides of the display just like the
> > gap
> > in RAM between the two lines of a 2-line display.
> >
> > If you're only seeing the left 8 characters on the display it is
> > likely
> > the x16 type.  There is no way to test with software what kind it
> is.
> >
>
> What I get when power it up and adjust the contrast, is 8 dark blocks
> left, and 8 lighter ones to the right.
>
> When I run Niki's program all 16 character become lighter - so I
> assume
> it is initialised.
> At this point, I can't get it to display anything else. I'll ask Niki,
> since I had to change one or two things to get MPASM to assemble it.
>
> Is it possible to destroy just the data display part of the LCD. I
> find
> it unlikely that soldering my pins on it could destroy the bugger.
>
> > Even without any commands from the PIC, the HD44780 will reset
> itself
> > into x8 mode and clear the display RAM at power-on.  So when the
> power
> > is
> > turned on and the LCD drive voltage sufficiently high (or low, since
> > it
> > is relative to Vdd), some or all of the characters should change to
> > dim
> > or dark blocks.  THis is a pretty good test of the LCD module.
>
> OK mine does that (allready mentioned)
>
> > If you
> > can't get anything at all on the screen you may have one of the
> > high-temperature modules which requires more than 5V of LCD drive.
> In
> >
> > that case the LCD drive pin needs to be pulled negative a few volts.
>
> But that would guarantee that a normal temp one would loose its
> smoke....
>
> Cheers! And thanks for the help!
>
> --
> Eric van Es               | Cape Town, South Africa
> mailto:vanes@ilink.nis.za | http://www.nis.za/~vanes
> LOOKING FOR TEMPORARY / HOLIDAY ACCOMODATION?
> http://www.nis.za/~vanes/accom.htm

I have an optrex 16117A LCD, That is configured like that.( 16x1,
configured as 2 logical lines.
To save I/O pins, I used a serial shift register (74HCT164) to send the
data to the LCD via it's 8-bit bus. (I could not get the 4-bit thing to
work). Since I dont see any reason to read data from the controller
(the  HD44780) this works for me. I have some test code that I used for
a PIC16C57 that works great.

If you are interested in the code Let me know and I will post it to the
PICList website. (http://www.428main.com/piclist/)

Alan Nickerson