说明：  课程设计要求设计并用FPGA实现一个数字频率计,功能：频率计。具有4位显示，能自动根据7位十进制计数的结果，自动选择有效数据的
(Curriculum design to design and FPGA implementation of a digital frequency meter, function: frequency meter. With four shows that will automatically count 7 the results of the metric system, automatic selection of effective data)