This Figure shows the MDIO ports of the GMII to RGMII core connected to the MDIO of an external PHY device. Here, mdio_phy_i, mdio_phy_o, and mdio_phy_t must be connected to a 3-state buffer to create a bidirectional wire, MDIO.
This 3-state buffer can either be external to the FPGA or internally integrated by using an IOB IOBUF component with an appropriate SelectIO™ interface standard suitable for the external PHY.
