Arduino LiquidCrystal_I2C library

Want to free up some ports of your Arduino but don't want to buy a new LCD?
Try this: convert your parallel HD44780 compatible LCD to I2C with just a few components.

All functions of the regular LiquidCrystal Library are supported (I think).
The library also has aliases for most of the functions listed in the LCD API 1.0 by Dale Wentz
Download the library here
If you want to use the library with the interface board sold by read this additional info

This library was released in 2009 and until this day no bugs have been reported. Most problems lead back to fauly cabeling or wrong addressing.
If you encounter bugs send me an email at

Update 12/2011: V2 release.
Due to the release of Arduino IDE 1.0 some changes were made to the library to get it working under the new IDE.
Because of these changes this version of the LiquidCrystal_I2C library can not be used for older IDE versions!
The Multiple display example is moved to the samples directory so it becomes available as a sample in the IDE.
(Thanks to Ailton F. for beta testing.)

The old V1.0 version of the LiquidCrystal_I2C library can be downloaded here.

Update 03-2013: Fixed an error in the schematic diagram.