StrangeParty demos how to use the Matrix Orbital 20×4 display with Arduino via I2C using the Wire library. The LK204-25 is a serial display, so connection to the Arduino requires just two wires to accept I2C commands and data. We expect this same procedure would work with other manufacturers’ I2C LCDs.
Simple and useful if you have a surplus serial LCD on hand, but not as inexpensive as using a parallel LCD with the LiquidCrystal library.