这是一个频率计的源代码，用的是VHDL语言设计的，能够测量0-20KHZ的频率！-This is a frequency meter of the source code, using the VHDL language design, can measure 0-20KHZ frequency!

这是一个使用VHDl编写的频率计程序，正确运行，值得一看，代码有详细说明-This is a preparation using VHDl frequency meter program to run properly, worth a visit, the code is described in detail