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'PIC 16c84 4bit LCD interface - I need help'
1998\02\26@074242 by Ralf Sigmund

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After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x
16 LCD display I desperately seek some help.
I tried to use the code snippet Dave Duley posted some time ago.
Unfortunately it just did not work.
Perhaps I failed, because the source covered only the used functions and no
main program...
The Microchip AN 587 example code uses a 16c5x device.
As the only Pic Controller I have here is a 16c84 I ran into serious
problems
because i do not know all the registers and ports they use.
I am not sure in what order I should connect the RB lines to the Display and
if I should use rb0-rb3 or rb4-rb7 as data lines.
I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8
bit interface without usage of the LCD R/W line.

Thanks for any help
Ralf

1998\02\26@084633 by Lauri Pirttiaho

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:After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x
:16 LCD display I desperately seek some help.
<etc...>

If you do not mind doing some actual coding yourself, the thing you
need is HD44780 manual. Now, fortunately, it is online. In

http://www.hea.com/hean2/lcdc/hd44780list.htm

at Hyundai pages you can find a rather complete manual for HD44780.
Notice the initilaization procedure, you need at the beginning.
You need that to set the 4-bit operating mode!

For 4-bit interface you need 7 lines: Enable, Register Select,
Red/Write and Data lines 4-7. Initiation of the 4-bit mode
is described in the "Initialization: By Instructions" link
and 8-bit data is written over the 4-bit interface with
most significant nibble first.

-- Lauri

---
<a href="http://www.ee.oulu.fi/~lapi/">For more info.</a>

1998\02\26@124602 by Steve Lawther

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    Ralf,
   
    see my test circuit and software for the 16C84 on
   
    http://ourworld.compuserve.com/homepages/steve_lawther/charlcd.htm
   
    This shows how to implement a 4 bit interface, and the test software
    gives you error codes, if it finds faults.
   
    Any problems, just shout.
   
               Steve Lawther
   


______________________________ Reply Separator _________________________________
Subject:      PIC 16c84 4bit LCD interface - I need help
Author:  MIME:spam_OUTralf.sigmundTakeThisOuTspamSTUD.UNI-HANNOVER.DE at INTERNET-HUSKY
Date:    26/02/98 14:56


After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x
16 LCD display I desperately seek some help.
I tried to use the code snippet Dave Duley posted some time ago.
Unfortunately it just did not work.
Perhaps I failed, because the source covered only the used functions and no
main program...
The Microchip AN 587 example code uses a 16c5x device.
As the only Pic Controller I have here is a 16c84 I ran into serious
problems
because i do not know all the registers and ports they use.
I am not sure in what order I should connect the RB lines to the Display and
if I should use rb0-rb3 or rb4-rb7 as data lines.
I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8
bit interface without usage of the LCD R/W line.
   
Thanks for any help
Ralf
   

1998\02\26@124607 by mike

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In message  <.....199802261345.PAA13729KILLspamspam@spam@tk8.oulu.fi> PICLISTspamKILLspamMITVMA.MIT.EDU writes:
{Quote hidden}

Minor correction, I think you'll find the Read?write line is not
needed and should be tied low IF you don't want to read from the
display.

Regards,

Mike

1998\02\26@221805 by Adi

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Hi Ralf,

I am just beginning to tackle the same project, interfacing a PIC to
a HD44780 using the 4 bit interface. I am using a 74HC595 to free up
some I/O on the PIC. Anyways, you are supposed to use DB4 to DB7.
B.G. Micro sells some 2x20 LCD displays and their datasheet for the
display has some helpful info about the 4bit transfer. Their website
is http://www.bgmicro.com. I could also send the file if you like...

Regards,
Adi

{Quote hidden}

1998\02\27@003829 by Mark Lezama

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Ralf, if you want to used the HD44780 in a 4 bit interface:

1.- You have to used DB4-DB7 in the module it doesnt matter if you conect
rb0-rb3 or rb4-rb7 but you have to be wiser in what way you are sending the
information.

2.- When you circuit startup wait at least 15ms before send any inormation to
the HD44780.

3.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF

4.-Wait at least 5ms.

5.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF

6.- Wait at least 100uS.

7.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF

8.- Put RS=0; R/W=0; dato=0010 (dato=DB7 DB6 DB5 DB4). this set 4 bit interface.
after this step you can check BF and have to send the commands for funtion sets,
etc.

Ralf Sigmund escribis:

{Quote hidden}

1998\02\27@015502 by Philippe
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At 13:29 26/02/98 +0100, you wrote:
>After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x
>16 LCD display I desperately seek some help.
>I tried to use the code snippet Dave Duley posted some time ago.
>Unfortunately it just did not work.
>Perhaps I failed, because the source covered only the used functions and no
>main program...

UMPS will help you to see why it does not work: it will simulate
the HC44780 LCD panel. Try it:

       http://www.sistudio.com/umps

Regards,
       Philippe.

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{Quote hidden}


'PIC 16c84 4bit LCD interface - I need help'
1998\03\03@202406 by Ron Kreymborg
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Ralf and Others

I started a project some time ago which included the requirement for a
2-line lcd display using a 4 line interface to a 16X84. Others on the
piclist helped me over a problem when I was setting the contrast
incorrectly (in fact not at all). The lcd module is now working well and
uses just 75 bytes (here a byte is 12 bits!).

For those who want to look at yet another lcd driver, it's on my web page
at http://www.shm.monash.edu.au/~r.kreymborg/pic/lcd.html and includes a test
program and all the necessary files in zip format to download.

Ron

On Thu, 26 Feb 1998, Ralf Sigmund wrote:

> After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x
> 16 LCD display I desperately seek some help.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ron Kreymborg                   Computer Systems Manager
Monash University               CRC for Southern Hemisphere Meteorology
Wellington Road
Clayton, VIC 3168               Phone     : 061-3-9905-9671
Australia                       Fax       : 061-3-9905-9689
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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