说明：  1.分析直流电机的机械特性，并掌握直流电机调速原理； 2.学习单片机工作原理、接口方法及编程方法； 3.学习PWM调速基本原理及软、硬件实现方法； 4.独立设计一个基于单片机的PWM直流电机调速系统，并用Proteus、Matlab等软件进行绘图与仿真； 5.分析仿真结果，提出改进方案。
(This paper introduces a kind of method of DC —motor speed modification based on PWM theory by the SCM．Showing some relative knowledge upon the DC—motor timing，the basic theory and the way to implement． And it emphasizes on the way for carrying out PW M signals based on MCS一5 1．This paper still provides a method for modifying the speed of DC—motor by way of taking count of data and time delay by software．It offers a sort of eficient method for the DC motor speed—controlling system)