This library is written from scratch and makes full use of the 8 bit capability of the MCP23017 to send multiple packets to the HD44780 in one transmission, minimizing the overhead of the two wire address and register commands. At a wire bus speed of 400 kHz throughputs of more than 5200 characters per second for single characters and up to 8100 characters per second for strings are reached.

This is nearly 11 times as the fast for single characters and nearly 17 times as fast for strings compared to the Adafruit library at the same bus speed.

It can print to the lcd and load special characters into the lcd directly from program memory with the printP and createCharP command.

The buttons have callback functions for short press, long press and repeating. There is also a static callback for two buttons pressed at the same time.

Please note that the RobotDyn LCD RGB 16x2 + keypad + Buzzer Shield can have either a normal controlled backlight (white rectancular led connection on the right side of the display) or a inverted controlled backlight (white trapezium shaped led connection on the right side of the display).

normal	inverted