通常直流电机由一串脉冲控制，通过调节脉冲的电平、持续时间可以使得电机正转、反转、加速、减速和停转。转动的原理：转动的方向由电压控制，电压为正电机顺时针转；电压为负电机逆时针转。转速的大小由输出脉冲的占空比决定，占空比大则转速大。-Usually the DC motor controlled by a string of pulses, by regulating the level of the pulse, the duration of the motor forward, reverse, speed up, slow down and stall. The principle of rotation: the direction of rotation is controlled by the voltage, the voltage of the motor are clockwise　voltage of negative motor counterclockwise. The size of the speed determined by the output pulse duty cycle, the duty cycle is large, the speed is large.