程序通过串口从主机获得控制信号——电动机选择信号，电动机转动方向以及电动机所需要运行的步数信号，并根据获得的相应的信号做出相应的动作。-Procedures through the serial port access control signal from the host- motor selection signals, the direction of motor rotation as well as the motor required to run the step signal,