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'Help 1X16 LCD only prints 8 characters!'
1999\01\20@162737 by Jon Petty

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Hello,

After all the post I've read concerning LCD's you'd think I could figure this
one out. I have got an optrex dmc 16117a w/ hitachi 44780 chip.

The lcd prints fine, a little dark when set for 1x16 mode, but lightens up
when I tried the 2X16 mode (for the heck of it), but still only prints 8
characters. I tried another display (same type) and it doesn't change.

I am in 4 bit mode and I believe I've tried every config.

What am I missing? Believe me I've spent a lot of time on this one before I
posted.

Thanks in advance

Jon

Help 1X16 LCD only prints 8 characters!

1999\01\20@164202 by kfisk

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I think you have to print the next 8 characters like they are on the second
line (this is just from memory from a long, long time ago). I'm sure others
will correct me if I'm wrong.

Cheers,

Kevin

{Quote hidden}

1999\01\20@170414 by Todd Peterson

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>Help 1X16 LCD only prints 8 characters!

On some 1x16 displays the right half of the display is mapped to the
'second' row in memory - you'll need to perform a cursor move to reach them
(see module datasheet).


Ê Todd Peterson
Ê E-Lab Digital Engineering, Inc.
Ê (816) 257-9954
Ê Embedded Control & Integrated Circuit Solutions...

http://www.elabinc.com

1999\01\20@171219 by ryan pogge

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did you get it from BG micro?
cause i think thats the one i got that does the same thing....
when you init it the whole top line goes dark black.
thats all i can get it to do ..hehe



>Hello,
>
>After all the post I've read concerning LCD's you'd think I could figure
this
{Quote hidden}

1999\01\20@180808 by paulb

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Jon Petty wrote:

> The lcd prints fine, a little dark when set for 1x16 mode, but
> lightens up when I tried the 2X16 mode (for the heck of it), but still
> only prints 8 characters. I tried another display (same type) and it
> doesn't change.

> I am in 4 bit mode and I believe I've tried every config.

 Bit confusing here.  There are no "1 x 16" or "2 x 16" modes, there is
a one-line mode and a two-line mode.  Which is it, and more particularly
how many lines and characters is the display?

 Darkness depends on the contrast control.  You do *have* a contrast
control fitted?

> Help 1X16 LCD only prints 8 characters!

 It sounds like you mean you have a 16-character 1-line display.  These
are (all?) implemented electrically, due to the chip architecture, as a
2 line by 8-character display.  They require setting up in two-line
mode, and the address of the start of the second line is $40.

Kevin Fisk wrote:

> I think you have to print the next 8 characters like they are on the
> second line (this is just from memory from a long, long time ago).
>  I'm sure others will correct me if I'm wrong.

 You're dead right Kevin, you must *set up* 2-line mode, and write
accordingly.

Todd Peterson wrote:

> On some 1x16 displays the right half of the display is mapped to the
> 'second' row in memory - you'll need to perform a cursor move to reach
> them (see module datasheet).

 Todd, can I quiz you on the word "some"?  Since to do so means adding
an extra chip and only using half the capability of each, have you
*ever* seen a display which *didn't* map as two lines?  They certainly
may exist, but would be special ones using the extended-height (11 pixel
high IIRC) character set, presumably LARGE displays.

Ryan Pogge wrote:

> did you get it from BG micro?
> cause i think thats the one i got that does the same thing....
> when you init it the whole top line goes dark black.
> thats all i can get it to do ..hehe

 Your reference to "whole top line" suggests to me 1} you have a two-
line display, 2} you are only initialising it for 1-line display and
2} you have the contrast control set wrong.  You *DO* have a contrast
control fitted, don't you?

 Frankly, the instruuctions for these things, *when* you find them
(I'll quote the sites again on request - really *must* put them on my
web page!) aren't terribly easy to understand.
--
 Cheers,
       Paul B.

1999\01\20@191159 by Jon Petty

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In a message dated 1/20/99 4:08:09 PM US Mountain Standard Time,
spam_OUTpaulbTakeThisOuTspammidcoast.com.au writes:

<<  It sounds like you mean you have a 16-character 1-line display.  These
are (all?) implemented electrically, due to the chip architecture, as a
2 line by 8-character display.  They require setting up in two-line
mode, and the address of the start of the second line is $40.
 >>


Any one have an example?

I guess I would have to count the characters. If characters are greater then 8
then a new address ($40)  would be written.

Is  the address written to DDRAM?

Thanks

Jon

1999\01\20@192028 by Jon Petty

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In a message dated 1/20/99 4:08:09 PM US Mountain Standard Time,
.....paulbKILLspamspam@spam@midcoast.com.au writes:

<<
Your reference to "whole top line" suggests to me 1} you have a two-
line display, 2} you are only initialising it for 1-line display and
2} you have the contrast control set wrong.  You *DO* have a contrast
control fitted, don't you?


Yes there is contrast control, but when I had the display set up for 1 line it
was very dark required min contrast setting to read. In 2 line mode it looks
fine.



Frankly, the instruuctions for these things, *when* you find them
(I'll quote the sites again on request - really *must* put them on my
web page!) aren't terribly easy to understand.

I agree, I found a lot of info on initialization. Got that without to many
problems. I thought writing to it would be the easy part.


Thanks

Jon


 >>

1999\01\21@061929 by Tracey Nickerson

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I had the same problem, I have the same LCD module.
Using a PIC16C57 in 8-bit mode with a shift register to control the LCD.
The solution is the address for the right half od the display. See the code
described below for the details. I have the Optrex data book if you dont,
and need more info.

In the PIC Code section on the PICLISt Web Archive Site I posted the code to
drive the LCD in this fasion. The code it well commented, see the
DISPLAY.ASM file

URL is: http://www.iversoft.com/piclist/

Alan Nickerson

{Original Message removed}

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