目前以太网PHY芯片是通过总线MDC/MDIO，但是基本上是通过MAC芯片直接管理的，本代码实现了通过FPGA管理PHY。即由FPGA完成MII管理-At present, Ethernet PHY chip through the bus MDC/MDIO, but basically through the direct management of MAC chip, the code through the FPGA implementation management PHY. FPGA