CHAPTER 27 ■ ENCORE
There are more complicated disc patterns, like Gray coding, from which the robot can tell the exact
position of the wheel and in which direction it is rotating. There are adapters for motors, called encoders,
which include a sensing technology and a circuit in a single enclosed piece.
Displays
Indicator LEDs are inexpensive, lightweight, and easy to add to a circuit. But, they only convey a limited
amount of information. On the other hand, multi-segment alphanumeric LEDs, character-based LCDs
(liquid crystal displays), and graphic displays are much friendlier and informative.
Character-based LCDs (see Figure 27-23) are available in a number of sizes, ranging from a small
display of 8 characters by 2 lines up to a display of 20 characters by 4 lines. Most character-based LCDs
communicate through an industry-standard 14-pin interface. Once you’ve learned how to control one,
there’s almost nothing more to learn to control the other sizes and styles.
Figure 27-22. A black and white patterned disc for determining wheel or shaft rotation
Figure 27-23. Standard 14-pin 20-character by 4-line LCD