利用AT89S51单片机的P0端口的P0.0－P0.7连接到一个共阴数码管的a－h的笔段上，数码管的公共端接地。在数码管上循环显示0－9数字，时间间隔0.2秒。(AT89S51 microcontroller using the P0 port P0.0 - P0.7 connected to a total Yin digital tube a - H pen section, digital tube common terminal ground. In the digital tube display cycle 0-9 number, time interval 0.2 seconds.)