Problem with Arduino UNO and 20x4 LCD Display

Other Hardware Displays
1

Hello,

I'm new to Arduino and electronics and I'm trying to get a 20x4 LCD Display working on my Arduino.
After wiring up (I think it's correct) I only got 2 rows of blocks and nothing more...line 1 and 3.
My guess is that the initialization in my code is correct, so it could be some wrong wiring. When you look at my attached Pics you will see that the Poti that controls contrast is on the correct Pins, so all wires should be correct. Unfortunately I have no Specs for this Display but maybe the Pictures I've made can help someone to give me a hint what the problem could be?

The Sketch I ran on my Arduino UNO is the Basic Liquid Crystal Sketch with changed initialization Pins:

#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(4,5,6,7,8,9);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(20, 4);
  // 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);
}

Can someone give me a hint what the problem might be?

Thank you

dragi

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LCD_Problem.png
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2

It is likely that the back light is the issue here, it is loading the power supply too much, I don't see a current limiting resistor. The usual value is 150 ohms. to test it pull a lead from 15 or 16 and see If the sketch will run, If you have black bars adjust the pot until they just disappear.

Doc

3

You forgot to connect pin 5 of the LCD module to GND.

Don

4

Hello,

thank you for your answers! After connecting Pin5 from the LCD to GND the Display shows something.
But it is not "hello world" like the sketch should but some something strange.
Do you have any idea what it shows and why?

thank you

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5

You probably have one or more of your four data lines connected incorrectly. If that checks out OK then try this sketch and see what it does:

#include <LiquidCrystal.h>

//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);      // put your pin numbers here

void setup()
  {
  lcd.begin(16, 2);                          // put your LCD parameters here
  lcd.print("hello, world!");
  lcd.setCursor(0,1)
  lcd.print("it works!");
  }

void loop()
  {
  }

Also - Did you deal with the current limiting resistor for the LED backlight?

And - Your contrast is not set properly. You should not be able to see the 'boxes' in the blank spaces and behind the characters.

Don

6

Hi,

first of all, it works now but I did not really do anything other then resetting the Arduino and uploading the sketch ones again.

I did not put in an Resistor for the Backlight yet...will it kill my LCD Backlight when not putting one in?

Thank you for your support! I love this community!

7

I did not put in an Resistor for the Backlight yet...will it kill my LCD Backlight when not putting one in?

Some LCD modules have the required resistor incorporated on the PC board. Your backlight does not appear to be excessively bright so it is possible that one of the resistors on the back of your LCD module is there for that purpose.

Don