Recent LCD Discovery

I recently visited an electronics surplus store while working in Minneapolis. This place was packed with electronic components. Bin after bin of switches, connectors, components and everything else you can imagine. I came across a bin full of LCDs that were not identified. $4.50 later, I was the proud owner of an unidentified LCD display. I knew it was new because a thin piece of protective plastic was still stuck to the front of the LCD display. :)

After getting to my hotel room that night, I started doing a little research online. I was disappointed to find very little information about the display - this is what I knew:

1. Manufacturer: Optrex

2. ID: PWB50244A-CEM printed on the display

3. Pin header has 15 pins

The only thing I could find was this data sheet, and it only identified a "DMC 50244". It also showed the display having a 4x20 display layout. In the data sheet, I found a pinout listing and decided to take a chance and see if it worked. 

 Here's the implementation using an Arduino Duemilanove.

Here is how I wired the display to the Arduino.

Display   Arduino
1         GND
2         5V
3         Variable Resistor Sweeper (10K)
4         12
5         GND
6         11
7         NC
8         NC
9         NC
10        NC
11        5
12        4
13        3
14        2
15        NC

I had trouble at first, nothing was showing up and I decided to look closer at the Vee pin specifications. I found very little from Optrex but did discover I needed to use a 10k variable resistor and dial in a proper contrast setting. This worked and the display came to life!

Here is the code I used to run this program.

#include <liquidcrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() 
{
  lcd.begin(20, 4);
  lcd.print("Optex PWB-50244-A");
  lcd.setCursor(32,0);
  lcd.print("LCD Display Example");
  lcd.setCursor(0,1);
  lcd.print("Arduino Duemilanove");
  lcd.setCursor(32,1);
  lcd.print("Mark Was Here!");
}

void loop() 
{
}

You'll notice I use "lcd.setCursor(32,0)" to position the cursor on the first column in the second line. That's because the LCD controller treats this display as a 2 line display (as far as I can tell) and requires you to treat the first column of the second line as the 32nd column of the first line. Odd. But it works.

I have not been able to figure out what pin 15 is for - I did try connecting it through a 1K resistor to both Vcc and Gnd. I was hoping there may be a back-light...but I discovered nothing. A little tracing on the board didn't seem to illuminate it's purpose either. Oh well - maybe one of you will know the answer! :)

Good luck finding unmarked parts and making them come to life! Let me know how it goes for you!