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