LCD Serializer README.TXT

This LCD project includes a small Printed Circuit Board that
"piggy-backs" onto an LCD display module with a "standard"
14-pin connector.  The LCD.ASM file is enough for a designer
to construct their own baord.  The KITS include my particular
board.  This board has the 14-pin connector (both 1x14 male
header as well as the 2x7 header are provided).  Also, a 
5-pin male header is where +5V and serial inputs must be 
supplied.  The board controls power to the LCD module.  The
board must be given an RS232 transmit signal through one
of the pins on the 5-pin header.  I have personally tested
this moule with standard PC ports, and it works fine.  The
input circuit drops the RS232 voltage down a bit, and the
RS232 negative voltage does not bother the PIC input pad
at all.  This 5-pin header is, by no means, a standard RS232
connector.  You must supply connections to your computer
or microcontroller.

LCD modules accept data and command instructions over a
special parallel TTL interface.  Command instructions 
include such actions like, cursor control, clearing, 
blinking, etc.  These commands are described in many LCD 
module data sheets or the Hitachi controller data sheet.
The point of the LCD Serializer is simply that this
parallel interface and the Hitachi initialization sequence
is awkward.  Too many pins must be devoted to the LCD, even
though a simple serial link is more than fast enough.  This
module allows you to use an LCD module through very simple
serial character manipulation.

The PIC basically, as you may confirm through the 
LCD.ASMcode, does the following.  On power-up, the PIC 
initializes the LCD module (a Microchip App Note also 
explains this basic process). The PIC then waits for a 
serial character (jumper selectable to either 2400 
or 9600 bps).  If the character is a special
escape character (0xFE), then the *next* character is assumed
to be a command.  The PIC will therefore pass the following
command to the LCD as a command.  Otherwise, the PIC simply
passes through data directly to the LCD.  This allows a host
program to write to the display, clear it, etc. simply by
interleaving data with escape characters.  Several example
host programs are included in the KITs.

The LCD Serializer is simple and cheap.  Why?  1) The 16C54 is
extremely cheap.  In fact, the 16C54 doesn't even include a 
UART and receives its serial by direct sampling.  2) The PIC
input ports do not require an RS232 driver for simply receiving
the RS232 characters.

To assemble the KITs, you will need only a soldering iron.  
Depending on which KIT you select, you may need to 
program a PIC or buy an LCD module.  All parts may be found 
in any Digikey catalog (http://www.digikey.com).  
The KITs always include the basic parts (like connectors, 
resistors, crystals, etc.), but again, may or may 
not include the PIC and the LCD.

KITs include a document with assembly instructions, theory 
of operation, and program listings of both the PIC code as well
several host program applications (including a PC C++ program
and a Visual Basic program).

ERRATA:
  - Some folks had trouble assembling this, where the problem
    was Assembler Options.  The code uses Default Radix of DECIMAL.
    Also, don't forget this program assumes 16C54 and XT (crystal
    option).  When I assemble, I get 0 errors/warnings, and I get
    3 common messages regarding W/F assumptions (not a problem).

  - If you burn your own PIC, don't hook RS232's +/- voltage
    directly on the PIC's inputs.  Ya might fry it.  My
    board has a voltage divider so that the RS232 is tamed
    to a nicer CMOS-friendly level.  If you want to be proper, use
    a real RS232 driver, like from MAXIM or almost anyone.

  - I don't outline all the LCD Controller commands.  There 
    are some summaries out there on the net.

Any questions?  email me if you do.