实验板中高两位和低两位数码管为两个独立计数器，利用键盘的两行按键通过外部中断方式分别控制它们的计数。每行选用三个按键分别作为一个计数器的启动、暂停、清0控制键。-High two and low-experimental board two digital tube into two independent counter, two rows of the keyboard keys by external interrupt, respectively, to control their count. Each row selected three keys, respectively, as a counter start, pause, cleared control keys.