Optrex C-51505 20x2 LCD issues

Other Hardware Displays
1

I'm new to the Arduino world and recently picked up a proMicro board.

The layout of the board is as follow:
https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide#hardware-overview-pro-micro

I've looked up the spec sheet for the LCD that I have
http://www.gaw.ru/pdf/lcd/lcm/Optrex/char/51505ade.pdf

and wired it accordingly for the LCD Hello world:

With some modifications (inspired by https://www.sparkfun.com/products/709#comment-50c4c1a4ce395fc170000000)
V0 (Vee for me - Power Supply for LCD Drive) is hooked up to a 4.7k resistor then to ground.
Backlight +/- are just hooked up to the 5v/GND

Basically all pins are shifted by 2 due to the backlight +/- being the first pin on the LCD.

My code is as follow:

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(14, 16, 10, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(20, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
}

The LCD does light up but I see no text displayed on the LCD. Do I need to pickup a potentiometer in order to 'adjust' the contrast to see the lettering?

I tried a few different setup with less backlight or smaller resistor with no luck. Anyone see anything wrong?

2

Do I need to pickup a potentiometer in order to 'adjust' the contrast to see the lettering?

Yes

V0 (Vee for me - Power Supply for LCD Drive) is hooked up to a 4.7k resistor then to ground.

Your problem is probably right here. Most likely the voltage at Vee is too high. It typically should be around 0.5 volts.

Your best bet is to use a potentiometer as recommended on page 9 of your data sheet.

A quick and dirty test would be to connect Vee directly to GND. This will typically give a usable but not optimal display.

Another option recommended by one of the other frequent contributors to this forum would be to use a potentiometer, connected as a rheostat (variable resistor) between Vee and GND.

Don

3

Thanks for the input - I'll pick one up to see if it helps!