这是双频测心率法的原理文档，做该项目时很有帮助-This is the dual principle of measuring heart rate law documents, the project is helpful to do

这是我自己用FPGA做过的等精度测频的主体思路，包括主要代码，没有数码管显示部分。肯定能用。-This is done for my own use FPGA and other precision frequency measurement of the main ideas, including the main code, there is no digital display section. Certainly can.