Using LCD modules with your Arduino Raspberry is popular, however the amount of wiring requires time and patience to wire it up correctly - and also uses a lot of digital output pins. That's why these I2C backpacks modules which only four wires - power, GND, data and clock. LCD modules that have a HD44780-compatible interface with various screen sizes.

Feature:

• HD44780 LCD interface compatible
  
• Suitable for most 1602 1604 2004 LCD module
• Many of Ardiuno Raspberry library support 
  
• I2C standard, work only 4 wires. VCC GND Data Clock
  
• 3 Pair solder pad for address select
  
• A short pin for LCD module back light ON and OFF 
• Adjustable LCD contrast
• I2C bus pull high on and off
• I2C chain port