LCD printing blocks

arduinolcdsolderingwire

Over the last couple days I have attempted to get my LCD to print "hello world". However for some reason not matter what code I upload from the liquid crystal examples on the Arduino program, it always prints blocks (shown below):
enter image description here

It has been an incredibly frustrating process, I checked that I have soldered all header pins properly and re-wired several times but I still get the same outcome. I have read on some websites that this is a problem due to my LCD being uninitialized. If this is the case, how do I initialize it?

Below are some photos of my LCD:
enter image description here

Best Answer

This appears to be the same module and may even be the tutorial you are following.

That tutorial gives sample code for writing to the LCD.

What you see on the LCD is what the tutorial shows happening when there's no communication with the Arduino.

Either your code is not correct (compare with code sample in the link given above) or the serial signals aren't getting to the LCD. Check your code, then double check the connections between the UNO and the LCD Module.

//code sample from http://www.dreamdealer.nl/tutorials/connecting_a_1602a_lcd_display_and_a_light_sensor_to_arduino_uno.html   
        #include <LiquidCrystal.h>

        LiquidCrystal lcd(7, 8, 9, 10, 11 , 12);

        void setup() {
          lcd.begin(16, 2);
          lcd.setCursor(0,1);
          lcd.write("LIGHT: ");
        }

        void loop() { }

Related Solutions

Electronic – arduino – Serial Enabled LCD

It really depends upon what you want to do with the Arduino, besides displaying information on the LCD. Like you, I used an HD44780-compatible LCD for my first project, and while it worked fine, it consumed half of my digital I/O pins, and seriously limited what I could do with my project. If you don't really need a lot of I/O, that can be fine.

On the other hand, if you want to do more than that, a serial LCD interface may make more sense. They cost twice as much, but as you can see from this example, you can daisy chain with I2C.

/* Quick example to use FunGizmos serial LCD in I2C mode
*
* Connections between LCD & Arduino 
* LCD P2
*   Pin1 not connected
*   Pin2 not connected
*   Pin3 SCL -> Analog in 5 (Arduino has internal pullup resistor)
*   Pin4 SDA -> Analog in 4 (Arduino has internal pullup resistor)
*   Pin5 VSS -> gnd
*   Pin6 VDD -> +5V
*
* To enable I2C mode of LCD Pads of R1 must be jumpered on back of LCD 
* (Between R6 & R14 right below the black IC glob)
*
*/

#include <Wire.h>

int lcd_addr = 0x50; //default I2C hex address from datasheet
int blink;

void setup(){
  delay(1000); //allow lcd to wake up.

  Wire.begin(); //initialize Wire library

  // Wire library expects 7-bit value for address and shifts left appending 0 or 1 for read/write
  // Lets adjust our address to match what Wire is expecting (shift it right one bit)
  lcd_addr = lcd_addr >> 1;

  //Send lcd clear command
  Wire.beginTransmission(lcd_addr);
  Wire.send(0xFE); //Cmd char
  Wire.send(0x51); //Home and clear
  Wire.endTransmission();

  Wire.beginTransmission(lcd_addr);
  Wire.send(0xFE); //Cmd char
  Wire.send(0x70); //Display LCD firmware version
  Wire.endTransmission();

  delay(2000);

  //Send lcd clear command
  Wire.beginTransmission(lcd_addr);
  Wire.send(0xFE); //Cmd char
  Wire.send(0x51); //Home and clear
  Wire.endTransmission();

  Wire.beginTransmission(lcd_addr);
  Wire.send("Hi I'm using I2C");
  Wire.endTransmission();

  Wire.beginTransmission(lcd_addr);
  Wire.send(0xFE); //Cmd char
  Wire.send(0x45); //Set Cursor pos
  Wire.send(0x40); //Line 2
  Wire.endTransmission();

  Wire.beginTransmission(lcd_addr);
  Wire.send("FunGizmos.com");
  Wire.endTransmission();

}



void loop(){

  Wire.beginTransmission(lcd_addr);
  Wire.send(0xFE); //Cmd char
  Wire.send(0x45); //Set Cursor pos
  Wire.send(0x40+15); //Line 2 last char
  Wire.endTransmission();

  Wire.beginTransmission(lcd_addr);
  if(blink)
     Wire.send('*');
  else
     Wire.send(' ');
  Wire.endTransmission();
  blink = !blink;

  delay(500);
}

Electronic – Arduino hooking up LCD without POT

You could start by using the variable resistor to find the sweet spot for the screen contrast, then use a multimeter to measure the resistance at that point, that should give you a good value for a fixed resistor. Otherwise you could look at using a digital potentiometer chip that could set the screen contrast and could be controlled by the Arduino

Best Answer

Related Solutions

Electronic – arduino – Serial Enabled LCD

Electronic – Arduino hooking up LCD without POT

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