扫描目标主机的各个端口，非常实用，而且非常简单

系统配置完，进入while(1)循环，开始扫描端口变化(上升沿)，如果有则进入相应的执行语句，采集端口信息，用了库函数此例程通过按键控制LED亮灭，熟悉了对端口的简单操作。-1, the system has finished configuration, enter the while (1) loop, start scanning port change (rising), if you enter the corresponding statement is executed