#####Ported to the Particle ecosystem by Mumblepins, as requested on this thread. I don't have the shield, so I'm relying on other people to report issues with it working. As suggested here by @anlek, pull-up resistors on the I2C lines may be necessary for use with the Core/Photon.
Pick one up at the Adafruit shop! ---------> http://http://www.adafruit.com/products/714
This new Adafruit shield makes it easy to use a 16x2 Character LCD. We really like the range of LCDs we stock in the shop, such as our classic blue & white as well as the fancy RGB negative and RGB positive. Unfortunately, these LCDs do require quite a few digital pins, 6 to control the LCD and then perhaps another 3 to control the RGB backlight for a total of 9 pins. That's half of the pins available on a classic Arduino!
With this in mind, we wanted to make it easier for people to get these LCD into their projects so we devised a shield that lets you control a 16x2 Character LCD, up to 3 backlight pins AND 5 keypad pins using only the two I2C pins on the Arduino! The best part is you don't really lose those two pins either, since you can stick i2c-based sensors, RTCs, etc and have them share the I2C bus. This is a super slick way to add a display without all the wiring hassle.
Adafruit invests time and resources providing this open source code, please support Adafruit and open-source hardware by purchasing products from Adafruit!
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, check license.txt for more information
All text above must be included in any redistribution
To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder Adafruit_RGBLCDShield. Check that the Adafruit_RGBLCDShield folder contains Adafruit_RGBLCDShield.cpp and Adafruit_RGBLCDShield.h
Place the Adafruit_RGBLCDShield library folder your /libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.