Nice setup 
I’ve got some breadboard setups with the same concept, added some eeprom read/write and analog/read commands for using the extra features as I’m sure you have as well.
I borrowed the code from http://www.nuelectronics.com/download/projects/lcd_smartie_v1.pde and just took away the extra code for buttons and such, then added the extra commands. Then I made a simple library for using the Arduino from the master Arduino with NewSoftSerial.
You can plug this into say an Arduino board, or other USB to serial converter, and then run the LCD-smartie program which enables you to control the LCD from the computer. They have examples of how to set it up here:
http://www.nuelectronics.com/estore/index.php?main_page=project_lcdsmartie
Here’s the sketch for the serial lcd, it uses the lcd4bit-mod library from nuelectronics.com(http://www.nuelectronics.com/download/projects/LCD4Bit_mod.zip)
Binary sketch size: 3974 bytes (of a 7168 byte maximum)
/* Serial LCD, using Matrix Orbital command set*/
// These must be changed in LCD4Bit_mod.cpp, this is just for reference
// RS, RW and Enable can be set to whatever you like
// int RS = 4;
// int RW = 13; // not used, ground the RW pin
// int Enable = 3;
// DB should be an unseparated group of pins - because of lazy coding in pushNibble()
// int DB[] = {5, 6, 7, 8}; //wire these to DB4~7 on LCD.
#include "LCD4Bit_mod.h"
#include <EEPROM.h>
//#include <Streaming.h>
const byte backLight = 13; // backLight for LCD: 69 = on, 70 = off
//create object to control an LCD.
//number of lines in display=1
LCD4Bit_mod lcd = LCD4Bit_mod(2);
void setup() {
pinMode(backLight, OUTPUT); //we'll use the debug LED to output a heartbeat
digitalWrite(backLight,HIGH); //turn backLight on
Serial.begin(9600);
lcd.init();
lcd.clear();
lcd.printIn(" LCD Ready: "); // Let you know LCD is ready
}
byte serial_getch(){
int incoming;
while (Serial.available()==0){
}
// read the incoming byte:
incoming = Serial.read();
return (byte) (incoming &0xff);
}
void loop(){
byte rxbyte;
byte temp;
byte addr;
byte pin;
int myVal;
int val;
rxbyte = serial_getch();
if (rxbyte == 254) //Matrix Orbital uses 254 prefix for commands
{
switch (serial_getch())
{
case 50: // Read analog pin, then send value back
pin = serial_getch();
myVal = analogRead(pin)/4;
delay(10);
Serial.print(myVal, BYTE);
break;
case 64: // EEPROM Write (address, value)
addr = serial_getch();
delay(10);
val = serial_getch();
EEPROM.write(addr, val);
break;
case 65: // EEPROM Read (address)
addr = serial_getch(); // EEPROM address
val = EEPROM.read(addr); //
Serial.print(val, BYTE);
break;
case 69: //backlight on (at previously set brightness)
// not implemented
digitalWrite(backLight, HIGH);
break;
case 70: //backlight off
// not implemented
digitalWrite(backLight, LOW);
break;
case 71: //set cursor position
temp = (serial_getch() - 1); //get column byte
switch (serial_getch()) //get row byte
{
//line 1 is already set up
case 2:
temp += 0x40;
break;
case 3:
temp += 0x14;
break;
case 4:
temp += 0x54;
break;
default:
break;
}
lcd.commandWrite(0b10000000 + temp);
break;
case 72: //cursor home (reset display position)
lcd.commandWrite(2);
break;
case 74: //show underline cursor
lcd.commandWrite(0b00001110);
break;
case 75: //underline cursor off
case 84: //block cursor off
lcd.commandWrite(0b00001100);
break;
case 76: //move cursor left
lcd.commandWrite(16);
break;
case 77: //move cursor right
lcd.commandWrite(20);
break;
case 78: //define custom char
lcd.commandWrite(64 + (serial_getch() * 8)); //get+set char address
for (temp = 7; temp != 0; temp--)
{
lcd.print(serial_getch()); //get each pattern byte
}
break;
case 83: //show blinking block cursor
lcd.commandWrite(0b00001111);
break;
case 86: //GPO OFF
//implement later
break;
case 87: //GPO ON
/*temp = serial_getch();
if (temp == 1)
{
GPO1 = GPO_ON;
}*/
break;
case 88: //clear display, cursor home
lcd.commandWrite(1);
break;
/*###############################################################
case 152: //set and remember (doesn't save value, though)
case 153: //set backlight brightness
//not implemented
break;
//these commands ignored (no parameters)
//case 35: //read serial number //USING FOR EEPROM//
//case 36: //read version number
case 55: //read module type
case 59: //exit flow-control mode
//case 65: //auto transmit keypresses
case 96: //auto-repeat mode off (keypad)
case 67: //auto line-wrap on
case 68: //auto line-wrap off
case 81: //auto scroll on
case 82: //auto scroll off
case 104: //init horiz bar graph
case 109: //init med size digits
case 115: //init narrow vert bar graph
case 118: //init wide vert bar graph
break;
###############################################################*/
default:
//all other commands ignored and parameter byte discarded
temp = serial_getch(); //dump the command code
break;
}
return;
} //END OF COMMAND HANDLER
//change accented char to plain, detect and change descenders
//NB descenders only work on 5x10 displays. This lookup table works
// with my DEM-20845 (Display Elektronik GmbH) LCD using KS0066 chip.
switch (rxbyte)
{
//chars that have direct equivalent in LCD charmap
/* case 0x67: //g
rxbyte = 0xE7;
break;
case 0x6A: //j
rxbyte = 0xEA;
break;
case 0x70: //p
rxbyte = 0xF0;
break;
case 0x71: //q
rxbyte = 0xF1;
break;
case 0x79: //y
rxbyte = 0xF9;
break;
*/ case 0xE4: //ASCII "a" umlaut
rxbyte = 0xE1;
break;
case 0xF1: //ASCII "n" tilde
rxbyte = 0xEE;
break;
case 0xF6: //ASCII "o" umlaut
rxbyte = 0xEF; //was wrong in v0.86
break;
case 0xFC: //ASCII "u" umlaut
rxbyte = 0xF5;
break;
//accented -> plain equivalent
//and misc symbol translation
case 0xA3: //sterling (pounds)
rxbyte = 0xED;
break;
/* case 0xB0: //degrees symbol
rxbyte = 0xDF;
break;
*/ case 0xB5: //mu
rxbyte = 0xE4;
break;
case 0xC0: //"A" variants
case 0xC1:
case 0xC2:
case 0xC3:
case 0xC4:
case 0xC5:
rxbyte = 0x41;
break;
case 0xC8: //"E" variants
case 0xC9:
case 0xCA:
case 0xCB:
rxbyte = 0x45;
break;
case 0xCC: //"I" variants
case 0xCD:
case 0xCE:
case 0xCF:
rxbyte = 0x49;
break;
case 0xD1: //"N" tilde -> plain "N"
rxbyte = 0x43;
break;
case 0xD2: //"O" variants
case 0xD3:
case 0xD4:
case 0xD5:
case 0xD6:
case 0xD8:
rxbyte = 0x4F;
break;
case 0xD9: //"U" variants
case 0xDA:
case 0xDB:
case 0xDC:
rxbyte = 0x55;
break;
case 0xDD: //"Y" acute -> "Y"
rxbyte = 0x59;
break;
/* case 0xDF: //beta //mucks up LCDSmartie's degree symbol??
rxbyte = 0xE2;
break;
*/ case 0xE0: //"a" variants except umlaut
case 0xE1:
case 0xE2:
case 0xE3:
case 0xE5:
rxbyte = 0x61;
break;
case 0xE7: //"c" cedilla -> "c"
rxbyte = 0x63;
break;
case 0xE8: //"e" variants
case 0xE9:
case 0xEA:
case 0xEB:
rxbyte = 0x65;
break;
case 0xEC: //"i" variants
case 0xED:
case 0xEE:
case 0xEF:
rxbyte = 0x69;
break;
case 0xF2: //"o" variants except umlaut
case 0xF3:
case 0xF4:
case 0xF5:
case 0xF8:
rxbyte = 0x6F;
break;
case 0xF7: //division symbol
rxbyte = 0xFD;
break;
case 0xF9: //"u" variants except umlaut
case 0xFA:
case 0xFB:
rxbyte = 0x75;
break;
default:
break;
}
lcd.print(rxbyte); //otherwise a plain char so we print it to lcd
return;
}
They use the Matrix Orbital Commands (minus some, such as auto-wrap functions and a few others, then add the first few that are shown above.)
You can then use the Master Arduino and connect it to the LCDs rx pin (and tx pin if you use the EEPROM and analog read functions) and use the examples shown here:
http://www.arduino.cc/playground/Learning/SerialLCD
Hope the code is helpful! (thanks for another write up :))
