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AR# 25033

Virtex-4 and Virtex-5 Embedded Tri-mode Ethernet MAC - Pullup required when simulating MDIO interface

Description

IEEE 802.3 specs section 22.2.2.12 states that an external PHY should provide a resistive pull-up on MDIO. "A PHY that is attached to the MII via the mechanical interface specified in 22.6 shall provide a resistive pullup to maintain the signal in a high state."

Solution

This pull-up is needed in simulation to correctly simulate the MDIO interface and can be added to the testbench as done in the Embedded Tri-mode Ethernet MAC wrappers Example design testbench. If a pull-up is not present, this will result in X's in simulation.

AR# 25033
Date Created 09/04/2007
Last Updated 05/21/2014
Status Archive
Type General Article