设计一个8位数字显示的简易频率计。能够测试1Hz~1MHz方正波信号的频率；电路输入的基准时钟为10MHz，测量值以BCD码形式输出；系统有复位键；-Design a simple 8-bit digital display frequency counter. Able to test 1Hz ~ 1MHz Fangzheng Bo signal frequency circuit input reference clock is 10MHz, the measured value in B