User manual

LPCXpresso Experiment Kit - User’s Guide

Page 63

7.9 Control a 7-segment Display

In this experiment you will learn how to control a 7-segment LED display. The component included in

the kit actually has two 7-segment digits. More about this further on. First, let’s have a look how a 7-

segment display works. The name 7-segment refers to the seven main segments, labeled A to G. See

picture below. Sometimes there is also an eighth LED, a dot that is typically labeled (R)DP. It is still

called a 7-segment LED even though there are actually 8 LEDs.

Figure 32 – Dual Digit 7-segment LED

The dual digit 7-segment LED that is used in this kit has common anodes and are multiplexed as

outlined in Figure 32. With the 7 LEDs it is possible to create digits 0-9 and the six first characters in

the alphabet. This makes it possible to display hexadecimal numbers. With the two digit display

included in the kit it is possible to display a byte value in hexadecimal form (0x00 – 0xFF).

Figure 33 – All Hexadecimal Digits

There are other types of LED displays. See the picture below. The 7-segment display is the simplest.

There are also 14- and 16-segment displays. With these it is possible to display all letters in the

alphabet. There are also matrix displays in different sizes. The 5x7 formation is the smallest to get

reasonable readable digits. The benefit with LED matrixes is that graphics can also be displayed.