The TWILCD is an easy to use dot matrix character display controller (backpack) that is controlled using the TWI (I2C compatible) protocol.

It is super-easy to control with any microcontroller that supports the TWI protocol. Libraries for Arduino and avr-gcc are available onGitHub.

The library is compatible with the Arduino LiquidCrystal library, so any sketch you have that uses a standard dot matrix display (with the HD44780 controller) can be converted to use the TWILCD with only 4 wires with only one single line of code change.

Only four wires are required for operation, one for power (runs on both 3.3V and 5V), one for ground, and two for the TWI protocol.

There are two different versions of the backpack board available:

  • TWILCD: Supports 1x16 and 2x7 connectors. It covers 16x1, 20x1, 16x2, 20x2 and 20x4 displays with and without backlight
  • TWILCD 40x2/40x4/RGB: Supports 1x18 connector (for Newhaven RGB backlit displays), 2x8 connector (used for some 20x4 displays) and 2x9 connector (used for 40x4 displays)

FEATURES, standard version

  • Available bundled with a display (two different displays available) or as a standalone board only to use with almost any dot matrix LCD display.
  • Contrast can be set in software - no potentiometer required
  • Backlight brightness can be controlled in software.
  • Arduino library fully compatible with the LiquidCrystal library available at GitHub)
  • Open Source Firmware (available at GitHub)
  • Programmable TWI Bus Address
  • On-board ISP header for upgrading firmware
  • Supports a wide variety of pinouts and displays

FEATURES, 40x2/40x4/RGB version

  • Includes all the features of the standard version
  • RGB backlight fully adjustable in software when used with a Newhaven RGB backlit display)
  • 40x4 displays supported seamlessly

40x4 displays use two HD44780 controllers, and are not directly supported by the standard LiquidCrystal Arduino library (extra wires and code required)

NOTE: RGB backlight support is designed for Newhaven RGB displays ([1] or[2]). Other displays may also work, but the RGB backlight must be configured as common cathode.