.. _LCD HD44780:

===========
LCD HD44780
===========

The LCD HD44780 is the lingua franca amongst
the display modules found around microcontrollers. They
need only 4 data bits and 3 control bit to work. Gerald Wodni
published a LCD driver module on `TheForth.net <http://theforth.net/package/lcd-hd44780>`__
which works with amforth as well.

The basic driver module needs only a few adjustments basically moving
the IMMEDIATE from within the definitions to rigth after the finishing
semicolon.

.. code-block:: forth

   \ Demo for using the library with Mecrisp on an MSP430G2553
   \ (c)copyright 2017 by Gerald Wodni<gerald.wodni@gmail.com>
   \ adapted for amforth on the same platform by Matthias Trute

   \ Wiring:
   \ LCD    uC
   \ D4  -- P2.0
   \ D5  -- P2.1
   \ D6  -- P2.2
   \ D7  -- P2.3
   \ RS  -- P2.4
   \ E   -- P2.5

   \ RW  -- GND

   \ #require 1-ms.frt
   \ #require ms.frt

   \ Ports
   $29 constant P2OUT
   $2A constant P2DIR

   : init-ports
      $3F P2OUT c!
      $3F P2DIR c! ;
   
   \ from bitnames.frt, modified
   : c-or! ( bm addr  -- )
     dup c@ rot or swap c! ;
   : c-and! ( bm addr -- )
     dup c@ rot invert and swap c! ;
   
   : lcd-mode-data ( -- )
     $10 P2OUT c-or! ;

   : lcd-mode-cmd ( -- )
     $10 P2OUT c-and! ;

   : lcd-nibble ( x -- )
     $F P2OUT     c-and!  \ clear data
     $F and P2OUT c-or!   \ set data
     1ms $20 P2OUT c-and! \ pulse E
     1ms $20 P2OUT c-or!
     1ms ;

   \ used in lib:
   : 0<> 0= 0= ;
   \ from the-forth.net
   \ #require lcd-hd44780.4th
   \ swap-dragon image (3 by 2 custom chars)
   create d0 $00 c, $02 c, $03 c, $07 c, $06 c, $00 c, $00 c, $0C c,
   create d1 $00 c, $00 c, $00 c, $00 c, $11 c, $11 c, $0A c, $1B c,
   create d2 $00 c, $08 c, $18 c, $1C c, $0C c, $00 c, $00 c, $0C c,
   create d3 $1F c, $1D c, $18 c, $10 c, $00 c, $00 c, $00 c, $00 c,
   create d4 $1B c, $1F c, $1F c, $0E c, $0A c, $0A c, $1B c, $00 c,
   create d5 $1F c, $17 c, $03 c, $01 c, $00 c, $00 c, $00 c, $00 c,

   : demo
      init-ports \ set ports
      2 lcd-init \ 2 line lcd
      d0 0 lcd-char \ transmit dragon custom chars
      d1 1 lcd-char
      d2 2 lcd-char
      d3 3 lcd-char
      d4 4 lcd-char
      d5 5 lcd-char
      lcd" theforth.net   "
      0 lcd-emit 1 lcd-emit 2 lcd-emit
      $40 lcd-ddram \ 2nd line
      lcd" amforthMSP430"
      3 lcd-emit 4 lcd-emit 5 lcd-emit ;

Calling the ``demo`` command displays some text and a nice swap dragon

.. figure:: LCD-HD44780.png