使用51单片机完成简单的直流电机的转速控制。程序已经调试通过。显示和输入模块是7279控制的数码管和矩阵键盘，转速反馈是码盘光电开关。-DC motor velocity control based on 51-microchip. The program has passed in the practical examination. Using digital leds and matrix keyboard controlled by 7279 as output and input.