The following 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.