Cyclone® V Hard Processor System Technical Reference Manual
18.3.3.1. MDIO Interface
The MDIO interface signals are synchronous to l4_mp_clk in all supported modes.
|   Signal  |  
         In/Out  |  
         Width  |  
         Description  |  
      
|---|---|---|---|
| emac_gmii_mdi_i |   In  |  
         1  |  
         Management Data In. The PHY generates this signal to transfer register data during a read operation. This signal is driven synchronously with the gmii_mdc_o clock.  |  
      
| emac_gmii_mdo_o |   Out  |  
         1  |  
         Management Data Out. The EMAC uses this signal to transfer control and data information to the PHY.  |  
      
| emac_gmii_mdo_o_e |   Out  |  
         1  |  
         Management Data Output Enable. This enable signal drives the gmii_mdo_o signal from an external three-state I/O buffer. This signal is asserted whenever valid data is driven on the gmii_mdo_o signal. The active state of this signal is high.  |  
      
| emac_gmii_mdc_o |   Out  |  
         1  |  
         Management Data Clock. The EMAC provides timing reference for the gmii_mdi_i and gmii_mdo_o signals on MII through this aperiodic clock. The maximum frequency of this clock is 2.5 MHz. This clock is generated from the application clock through a clock divider.  |