通过P1.0口来控制直流电机的旋转的快慢 在数码管的最后一位显示档位，按S19按键，会调一个档位，并且直流电机的转速会发生变化-By P1.0 port to control the speed of rotation of the DC motor the last one in the digital tube display stalls, according to S19 button will bring up a gear and DC motor speed will cha