TABLE OF CONTENTS In this chapter, I provide you with a software module that will allow you to interface with character LCD (Liquid Crystal Display) modules. This software package works with just about any character module based on the Hitachi HD44780 Dot Matrix LCD Controller & Driver. The module allows you to:
Control LCD modules containing up to 80 characters.
Display ASCII characters.
Display ASCII strings.
Define up to eight symbols based on a 5x7 dot matrix.
Display bargraphs.
Liquid Crystal Displays (LCDs) are a passive display technology. This means that LCDs do not emit light but instead manipulate ambient light. By manipulating this light, LCDs can display images using very little power. This characteristic has made LCDs the preferred technology whenever low power consumption is critical. An LCD is basically a reflective part. It needs ambient light to reflect back to a user's eyes. In applications where ambient light is low or nonexistent, a light source can be placed behind the LCD. This is known as backlighting.
Backlighting can be accomplished by either using electroluminescent (EL) or LED light sources. EL backlights are very thin and lightweight and produce a very even light source. EL backlights for LCDs are available in a variety of colors with white being the most popular. EL backlights consume very little power but require high voltages (80 to 100 Vac). EL backlights also have a limited life of about 2,000 to 3,000 hours. LEDs are used for backlighting...
