Building an Interface for Serial LCD

The purpose of this project is to develop a front end means of interfacing with the LCD wherein it will accept serial data from the microcontroller with only one wire required.

Most of the text displaying LCDs are based on the HD44780A LCD controller which uses an 8-bit bi-directional interface and the other three control lines to connect with the host microcontroller. The HD44780 also supports a 4-bit interface aside from the 8-bit interface. The difference with the 4-bit mode and 8-bit mode is that two cycles are being done in the data transfers between the LCD controller and the MCU.

The behavior of the LCD can be controlled by the HD44780 which provides the user with some commands. The 3 different functional blocks contained in the LCD module includes the Display Data RAM (DD-RAM), Character Generator RAM (CG-RAM), and Character Generator ROM (CG-ROM). The characters that are displayed on the LCD is held by the DD-RAM which is the most important/complex of the function blocks. The user is allowed to define up to 8 special characters that are not included in the CG-ROM (which contains the 208 characters) using the CG-RAM.

Rest of the project