The paper introduces a basic kind of method of DC-motor speed modification based on PWM theory. Showing some relative knowledge upon DC motor speed modification, the PWM theory and the way to implement. It emphasizes on the way for carrying out PWM signals based on MCS-51. Taking 8051 Single Chip Micyoco as core and the little direct current motor as control object, the single closed loop speed control and PID control were realized. In the convenient man-machine interaction interface,the control signal and parameter were inputted with keybaord.so that the start and brake of motor and speed regulation were also realized. Provided main electric circuit principle diagram and each parts of electric circuit principle diagram, mainly include electric circuits MCS-51s, power supplies, keyboard and manifestation electric circuit, drive electric circuit, draw a procedure flow chart finally.
Keyword: MCS-51 ;PWM ;Hardware ;DC Motor