72 www.xilinx.com Embedded Tri-Mode Ethernet MAC User GuideUG074 (v2.2) February 22, 2010Chapter 3: Client, Host, and MDIO Interfaces RHost InterfaceTo access the Ethernet MAC registers through the host interface, the user must setTIEEMACCONFIGURE[67] = 1. The host interface allows the user to:• Program the configuration registers in the Ethernet MAC• Read the accumulated statistics from the statistics unit implemented in the fabric(optional)• Access the configuration registers and multicast address table register in the addressfiltering unit• Access the Management Data I/O (MDIO) registers of the physical componentsattached to the Ethernet MACsThe two Ethernet MACs share a single host interface. The host interface brings the EthernetMAC host bus from the Ethernet MAC out to the fabric. The host interface unit alsocontains a DCR bus bridge. This allows the user to access the Ethernet MAC registersthrough the DCR bus. Figure 3-38 shows the internal structure of the host interface. TheEMAC1 signal is provided by the HOSTEMAC1SEL input signal when using the generichost bus or generated by the DCR bridge when using the DCR bus.The DCREMACENABLE signal is used to select either the generic host bus or the DCRbus. When this signal is asserted, the host interface uses the DCR bus.Figure 3-38: Host InterfaceDCRBridgeEMAC1EMAC0Host InterfaceGeneric Host BusDCR BusDCREMACENABLE1 01 0Ethernet MAC BlockProcessor BlockVirtex- 4 FPGAPPC405DCRHOSTDONEIREMAC1ug074_3_40_080805www.BDTIC.com/XILINX
