Can't intialize LCD I2C with Arduino Micro

Hi everyone,

I’m trying to get this display working with my Arduino Micro. I’ve tried with every LCD I2C library, but I can’t get it initialized even with the example sketches. The backlight turns on, but the display is blank. Turning up the contrast pot it just shows 1 row of “blocks”.

Searching online it seems like a common problem, but I couldn’t find the solution anywhere.


VCC → 5V
SDA → Analog 4
SCL → Analog 5

The address should be 0x27 since all the address contacts things on the driver board are left open.

Example code from LiquidCrystal_I2C library

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup()
	// initialize the LCD

	// Turn on the blacklight and print a message.
	lcd.print("Hello, world!");

void loop()
	// Do nothing here...

The display is new, I don’t think it’s broken

Go on. The Arduino Micro has pins marked SDA and SCL (i.e. D2 and D3) marked as 2 and 3

Connect to the correct Hardware pins.


There is no contest. Install hd44780.h library via the IDE Library Manager

The random classes named LiquidCrystal_I2C classes are a nightmare.


if it doesn't work use a I2C Scanner to identfiy the real I2C address.
I2C Scanner MUST be able to see the a working device on the bus. Otherwise any other library will not work either.
And finally: Provide a real picture of your wiring, where we can see EACH wire and component of your setup.

I really recommend the hd44780 library. For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.

Install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE menus, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.

The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.

In the examples, there is a diagnostic sketch that will help us to help you if you still have trouble with the display. Run the diagnostic sketch and post the results.

The first thing to run after installing the hd44780 library is the included I2CexpDiag sketch from the hd44780_I2Cexp i/o class examples to verify that everything is working.

The first thing to do after installing the hd44780 library would be to spend a few minutes reading the included documentation.
— bill