Configuring the Ethernet MAC to the Correct Speed - 9.0 English

Tri-Mode Ethernet MAC LogiCORE IP Product Guide (PG051)

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9.0 English

When operating in tri-mode, the PHY negotiates the highest speed available with its link partner. The user application can set the speed of the Ethernet MAC after auto-negotiation completes by doing the following:

  1. The user application can either monitor auto-negotiation interrupt from the external PHY or internal Ethernet 1G/2.5G PCS/PMA or SGMII core or poll for auto-negotiation (see the relevant PHY documentation).
  2. When auto-negotiation completes, the user application can read the MDIO auto-negotiation registers to obtain the negotiated speed.
  3. The user application then needs to set this speed in the Ethernet MAC configuration registers using the host interface.

If auto-negotiation is disabled, the Ethernet MAC, PHY, and the PHY link partner must all be set to the same speed.