单片机完成两个功能：电机测速与频率测量，电机测速部分：单片机输出脉宽可调的方波控制电机速度，同时数码管显示电机的速度值。频率计部分：单片机完成对外部信号频率的测量，测量范围从2hz到10mhz，并通过数码管显示频率值。-MCU to complete two functions: motor speed and frequency measurement, the motor speed parts: the microcontroller output square wave pulse width adjustable motor speed control, digital display while the motor speed value. Frequency counter parts: MCU to complete the external signal frequency measurement, measuring range from 2hz to 10mhz, and through the digital display frequency.