FPGA平台下基于Nios II的数字频率计，测频模块采用verilogHDL编写，等精度算法，Avalon总线封装，Nios II读取最终的频率数值，显示在LCD12864上。-The Nios digital frequency meter based on II FPGA platform, the frequency measurement module written by verilogHDL, such as the accuracy of algorithm, Avalon bu