4-Pin I2C LCD Display

If you've completed one of the Arduino starter-projects you'll probably be familiar with the use of simple LCD-displays. They're great for showing (readable) information, but the downside is that they tend to be fiddly to wire up.

A great solution to this problem involves the use of an LCD which is controlled over the I2C bus - which means there are far-fewer wires to connect.

Hardware

The appeal of this hardware is that it only requires four wires to setup:

• Vcc
• Grnd
• Arduino
  • SCL to A5 on the Arduino.
  • SDA to A4 on the Arduino.
• WeMos Mini D1
  • SCL to D1 on the WeMos Mini D1.
  • SDA to D2 on the WeMos Mini D1.

I've seen this hardware in two forms - with an external board, or with a daughter-board connected to the back. Here are images of both kinds:

I2C LCD Driver

The software to drive the display can be found here:

• https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library

The library includes a bunch of examples, which you can load in the usual way, and one interesting thing about this library is that the backlight can be turned on or off, programmatically :)

A complete sample looks like this:

#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
  lcd.begin();

  // Turn on the blacklight
  lcd.setBacklight((uint8_t)1);

  // First row
  lcd.print("Hello, world!");

  // Second row
  lcd.setCursor(0,1);
  lcd.print("Steve Kemp");
}

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

Download the code.

Challenges?

Wire up an Infra-Red receiver, and write code to display the buttons you've pressed on the screen.

• Here is my solution.