LED code table and segment code table

LED is divided into two structures: common anode and common cathode, as shown in Figure 1 (b) and Figure 2 (c). If it is a common anode structure, the digital display (a~g) is effective when a low level is applied; if it is a common cathode structure, the digital display is effective when a high level is applied. Different combinations of 7 light-emitting segments can display 16 alphanumeric characters from 0 to 9 and A to F, thereby realizing the display of hexadecimal numbers. Table 1 and Table 2 are the font codes of 0 to 9 for common anode and common cathode respectively.

Figure 7-segment LED display device

Table 1 Common anode coding table

Table 2 Common cathode code table

Continued

The 7-segment display block is very easy to interface with a microcomputer. Just connect an 8-bit parallel output port to the LED pin of the display block. The 8-bit parallel output port outputs different byte data to obtain different numbers or characters, as shown in Table 3. The 8-bit byte data that controls the LED is usually called the segment selection code, and the segment selection codes of the common anode and the common cathode are complementary to each other.

Table 3 Seven-segment LED segment selection code