ABSTRACT
Liquid crystal displays (LCD) are devices frequently used for alphanumeric output in microcontroller-based embedded systems. According to their interface, LCDs are classified into serial and parallel. Serial LCDs require less I/O resources but execute slower than their parallel counterparts. The HD44780 is a dot-matrix LCD controller and driver. The following hardware elements form part of the HD44780 controller: two internal registers labeled the data register and the instruction register, a busy flag, an address counter, a RAM area of display data, a character generator ROM, a character generator Random Access Memory, a timing generation circuit, a liquid crystal display driver circuit, and a cursor and blink control circuit. The controller itself is often referred to as the MPU in the Hitachi literature. LCD programming is usually device specific. Before attempting to write code, the programmer should become familiar with the circuit wiring diagram, the setup parameters, and the specific hardware requirements.
