说明：  ７段数码管测试实验１：以动态扫描方式在８位数码管“同时”显示０--7 实验的目的是向用户介绍多个数码管动态显示的方法。 动态显示的方法是，按一定的频率轮流向各个数码管的COM端送出低电平，同时送出对应的数据给各段。
(7-segment test experiment 1: 8-bit dynamic digital scanning mode in the pipe " while" display 0- 7 experiment is introduced to the user multiple digital dynamic display method. Dynamic display method is to rotate at a certain frequency of the various digital control of the COM to send low end, while the corresponding data sent to each segment.)