这是利用FPGA来测量频率的，把两路信号经过异或后变成方波，然后测高脉宽的个数和整个周期的脉宽数，算出占空比即相位，最后把数据传到单片机上显示出来。-This is used to measure the frequency of the FPGA, the two signals through different or later into a square wave, and then measured the number of