This file describes the public interface of the low-level LCD driver that interfaces to the HD44780 LCD controller. Public functions are available to initialize the controller into 4-bit mode, to wait for the controller's busy bit to be clear, and to read or write one byte from or to the controller.

As there are two different forms of controller IO, one to send a command or receive the controller status (RS signal clear), and one to send or receive data to/from the controller's SRAM (RS asserted), macros are provided that build on the mentioned function primitives.

Finally, macros are provided for all the controller commands to allow them to be used symbolically. The HD44780 datasheet explains these basic functions of the controller in more detail.