用小开关用于模拟代替扫描开关，当有产品经过时，会使开关送出低电平，每按一下便会使数码管上的计数器加一，实现模拟工厂里的产品扫描计数器的功能。-With a small switch is used in place of the analog scanner, when the product passes, the switch will send a low level, each click will make the digital counter is incremented by o