数字频率计

代码说明：

说明：  设计一简易数字频率计，其基本要求是： 1)测量频率范围0～999999Hz； 2)最大读数999999HZ,闸门信号的采样时间为1s；. 3)被测信号可以是正弦波、三角波和方波； 4)显示方式为6位十进制数显示； 5）具有超过量程报警功能。 5)输入信号最大幅值可扩展。 6）测量误差小于+-0.1%。 7)完成全部设计后，可使用EWB进行仿真，检测试验设计电路的正确性。(The basic requirements of designing a simple digital frequency meter are: 1) The measuring frequency range is 0-999999 Hz. 2) The maximum reading is 999999HZ, and the sampling time of gate signal is 1 s. 3) The measured signal can be sine wave, triangle wave and square wave. 4) The display mode is 6-bit decimal number display. 5) It has alarm function beyond range. 5) The maximum amplitude of input signal can be expanded. 6) The measurement error is less than +0.1%. 7) After completing all the design, EWB can be used to simulate and test the correctness of the circuit.)