Visible to Intel only — GUID: prq1481130201563
Ixiasoft
Visible to Intel only — GUID: prq1481130201563
Ixiasoft
17.2. EMAC Block Diagram and System Integration
EMAC Overview
Each EMAC contains a dedicated DMA controller that masters Ethernet packets to and from the System Interconnect. The EMAC uses a descriptor ring protocol, where the descriptor contains an address to a buffer to fetch or store the packet data.
Each EMAC has an MDIO Management port to send commands to the external PHY. This port can be implemented using the I2C modules in the HPS or the EMAC's MDIO interface.
Each EMAC has an IEEE 1588 Timestamp interface with 10 ns resolution. The Arm* Cortex-A53 MPCore processor can use it to maintain synchronization between the time counters that are internal to the three MACs. The clock reference for the timestamp can be provided by the Clock Manager (emac_ptp_clk) or the FPGA fabric (f2h_emac_ptp_ref_clk). The clock reference is selected by the ptp_clk_sel bit in the emac_global register in the system manager.