HD44780 LCD-Interface

In this article I would like to explain the basics of the display controller and show how a simple interface can be designed in VHDL.

The HD44780 is a de facto or quasi-standard for the control of alphanumeric dot matrix LCDs, which was developed by Hitachi several years ago. The controller has a display data RAM (DDRAM) that can store up to 80 8-bit characters. The content of the RAM is shown on a dot-matrix display via a 16-line, 40-column LCD driver that can be expanded with additional display controllers or corresponding drivers (e.g. HD44100).