Description

Darn that Adafruit! We had been stirring the pot on a similar project, because it’s just so common-sense to do. But they beat us to the punch, and we’ll carry their product instead.

The wonderful idea is a simple backpack module that is installable to most character LCD units, and make it easy to use with a minimum of communication lines. This backpack uses simple i2c and SPI input/output expanders to reduce the number of I/O lines to as few as 2 (using I2C), and Adafruit has even written an easy-to-use Arduino library that is backwards compatible with projects using the ‘6 pin’ wiring.

This backpack will work with any ‘standard’ character LCD, from 8×1 to 40×4 sizes! As long as they have a 16-pin single-line connection header at the top.

For advanced users, this project can be used for general purpose I/O expansion, the MCP23008 has 8 i/o pins (7 are connected) with optional pull-ups, the SPI 74HC595 has 7 connected outputs.

Links:
Detailed tutorial on usage, including an Arduino library, wiring diagrams, and files
Wiring up a character LCD to an Arduino