I don't like powering backlights on LCD's with just the pin, the 4x20 LCD I have, backlight runs close to 60ma!! That's a bit too much for the Arduino pins, I generally choose a transistor.
Just wanted to point out, if you want to use your Arduino with LCD-Smartie, you can use the code from nuelectronics.com, here's the code I've used so far, it works fairly good but only supports Hardware serial atm:
(you can ignore the first 3 commands, I added those so I can control the LCD with an Arduino, and still read the analog ports and use the eeprom on board:D)
Here's the library required for the sketch:
http://www.nuelectronics.com/download/projects/LCD4Bit_mod.zip
You can edit the pins through the library, and here's where I borrowed the sketch. (I took out the buttons and such, since it's a standalone controller)
http://www.nuelectronics.com/download/projects/lcd_smartie_v1.pde
After you've got it uploaded, download LCD-smartie http://lcdsmartie.sourceforge.net/
Install, blah blah, then run the setup, choose Matrix.dll, then put in your com port and speed the arduino is using. (for more instructions:
http://www.nuelectronics.com/estore/index.php?main_page=project_lcdsmartie)
#include "LCD4Bit_mod.h"
#include <EEPROM.h>
//#include <Streaming.h>
const byte backLight = 13;
//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);
Serial.begin(9600);
lcd.init();
lcd.clear();
lcd.printIn(" LCD 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;
}