说明：  利用实验仪上的D/A变换电路，输出-8V至+8V电压，控制直流电机。改变输出电压值，改变电机转速。用8051的定时器0生成单位时间，由定时器/计数器1对单位时间内的脉冲计数，计算电机转速。参考数码管实验，将电机的实际转速在数码管上显示出来。
(Experimental apparatus on the D/A converter output voltage of-8V to+8 V, control DC motor. Change the output voltage to change the motor speed. 8051 Timer 0 with the unit of time generated by the Timer/Counter 1 on the pulse count per unit time to calculate the motor speed. Reference to the digital control experiment, the actual speed of the motor control on the digital display.)