由于目前所用到的FPGA器件以Altera的为主，所以下面的例子也以Altera为例，工具组合为 modelsim + LeonardoSpectrum/FPGACompilerII + Quartus，但原则和方法对于其他厂家和工具也是基本适用的。(Because the FPGA devices currently used are mainly Altera, so the following example takes Altera as an example. The tools are Modelsim + LeonardoSpectrum/FPGACompilerII + Quartus, but the principles and methods are basically applicable to other manufacturers and tools.)