I am having an issue with the LCD1602A and Arduino Uno. I have followed a tutorial on youtube that has got the device working, however the LCD is only displaying white blocks in all 16 segments of the top row.

Failure Image

Pin Out


  • VSS -> GND on Breadboard
  • VDD -> 5V on Breadboard
  • V0 -> Connected to 5K potentiometer
  • RS -> Pin 1 on Arduino Uno
  • RW -> GND on Breadboard
  • E -> Pin 2 on Arduino Uno
  • D0 -> Not Connected
  • D1 -> Not Connected
  • D2 -> Not Connected
  • D3 -> Not Connected
  • D4 -> Pin 7 on Arduino
  • D5 -> Pin 6 on Arduino
  • D6 -> Pin 5 on Arduino
  • D7 -> Pin 4 on Arduino
  • A -> 5V on Breadboard
  • K -> GND on Breadboard


#include <LiquidCrystal.h>
LiquidCrystal lcd(1, 2, 4, 5, 6, 7); // Creates an LC object. Parameters: (rs, enable, d4, d5, d6, d7) 
void setup() { 
 lcd.begin(16,2); // Initializes the interface to the LCD screen, and specifies the dimensions (width and height) of the display } 
void loop() { 
 lcd.print("Arduino"); // Prints "Arduino" on the LCD 
 delay(3000); // 3 seconds delay 
 lcd.setCursor(2,1); // Sets the location at which subsequent text written to the LCD will be displayed 
 lcd.clear(); // Clears the display 
 lcd.blink(); //Displays the blinking LCD cursor 
 lcd.noBlink(); // Turns off the blinking LCD cursor 
 lcd.cursor(); // Displays an underscore (line) at the position to which the next character will be written 
 lcd.noCursor(); // Hides the LCD cursor 
 lcd.clear(); // Clears the LCD screen 

Now the program compiles and uploads OK the potentiometer dims the blocks perfectly fine.

However it is supposed to print Arduino and 12345 and I am unsure why.

What am I missing?


  • Check your contrast Settings. – Kwasmich May 29 at 11:22
  • Checked contrast settings using potentiometer no luck. These only dim the blocks. – Mr Digs May 29 at 11:35
  • 1
    Your pin out text does not match the pin assigment in the lcd() line. Should be LiquidCrystal lcd(1,2,7,6,5,4), e.g., your data wires are flipped. – towe May 29 at 13:21
  • Thanks for your help. – Mr Digs May 30 at 7:02

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