Interfacing Arduino with a Purdy LCD (4×40) - Modified LCD4Bit Library
April 13th, 2008 by TheKidd
So I managed to grab a Purdy LCD sample (thanks to LadyAda’s page) to test Arduino interfacing. The first problem I ran into was that my LCD has two LCD controllers (KS0066 - based on HD44780). Thankfully lega7 faced this issue and modified code to work with a 4 line LCD.
I started with that but decided I wanted to modify his library to provide a few different advantages for my design. First of all, I set it up so the developer could pass the library all of the pins and other variables depending on their specific LCD. I also added a few additional functions including an easy debug function, right scroll function, and number functions.
A lot of this is still under testing so I will update this post as I improve the library and learn more about C/C++/C#. Hopefully it will work with other screens easily. This I have not tested yet as I only have one LCD at the moment. Its all kind of crazy at the moment because my background in programming is non-existent. I can read code but don’t know if I’m writing it properly yet. Then again, thats what I like about microcontrollers. I can build circuits and code and actually see it happen. Its definitely got me interested again in becoming a better programmer and engineer.
So anyway, moving on…Here is the Arduino code I’m currently working with.
#include <LCD4Bit.h>
// Constants
#define DEBUG_LED = 13;
// Variables: Program definitions for user configurable settings.
int lcdRows = 4;
int charactersPerLine = 52;
int dotFormatPtn = 0×00; //5×7 dots. 0×04 is 5×10
int usingRW = false;
int registerSelect = 6;
int readWrite = 7;
int enablePin1 = 0;
int enablePin2 = 1;
const int NUM_DB_PINS = 4;
int dataBits[NUM_DB_PINS] = {2, 3, 4, 5};
int test;
LCD4Bit lcd = LCD4Bit(lcdRows, charactersPerLine, dotFormatPtn, usingRW, registerSelect, readWrite, enablePin1, enablePin2, dataBits, NUM_DB_PINS);
void setup(){
pinMode(13, OUTPUT); //we’ll use the debug LED to output heartbeat
lcd.init();
lcd.clear();
lcd.cursorTo(3,0); //select second displaycontroller, line 3, 4
lcd.init();
lcd.clear();
}
void loop(){
digitalWrite(13, HIGH); //light the debug LED
lcd.cursorTo(1,0);
lcd.printIn("WTF is up with this");
lcd.cursorTo(2,10);
lcd.printIn("Num of Lines: ");
char buf[3];
//lcd.printIn(itoa(charactersPerLine, buf, 16));
lcd.numberWrite(charactersPerLine);
lcd.cursorTo(3,0);
lcd.printIn("To Visual C++ I go.");
lcd.cursorTo(4,0);
lcd.printIn(itoa(25, buf, 16));
/* lcd.printIn("Debug: ");
lcd.debugVariables(); */
delay(1000);
lcd.cursorTo(1,0); // select first two rows
lcd.leftScroll(40, 80); //scroll first two rows
//lcd.cursorTo(3,0); //select second displaycontroller, line 3, 4
//lcd.leftScroll(40, 80); //scroll third and fourth row
delay(5000);
digitalWrite(13, LOW);
}
And I’ve zipped up and attached the current modification to the LCD4Bit library. Again, this is so not ready for anything serious. I need to add comments to the Wiring code and work a lot more on the library. I’ll work on all that.
My next major mod to the LCD4Bit code will be to get it working properly with a shift register. This is important as I need to keep Arduino pin usage to a bare minimum to ensure there is also room for Xbee, RFID, a keypad, and GPS.
Haha, this will definitely be interesting.
