Working with Liquid Crystal Display

Although a display is not required to make an Arduino-based data collection device, it is very useful to be included. It works like a simplified computer monitor which facilitates human–machine interaction and provides the users with feedback and status updates or real-time data as the sensors collect information. For Arduino electronic projects, a commonly used inexpensive display is based on the technology of liquid crystal display or LCD for short. It has a flat glass panel and is lit by a backlight to show pixels that form letters, digits, or even images. What we are going to use are some of the simplest LCDs with two or four rows, although there are more sophisticated versions. They are character LCDs that only print characters (letter, numbers, and ASCII symbols), not images. There are LCDs that can draw images with Arduino boards, but our focus is to have the simplest way to communicate with the Arduino board with relatively straightforward coding. Figure 5-1 is a picture of a mono color 20×4 character HD44780 LCD with 16 connections that require soldering. It can display up to four rows of 20 characters.