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Intel® 82545/82546 Dynamically Changing Link Modes

Intel® 82545/82546 GbE Controllers: Dynamically Changing Link Modes


The Intel® 82545EM/82545GM and Intel® 82546EB/82546GB Gigabit Ethernet Controllers contain three link modes of operation. The first incorporates the use of an internal fully IEEE-compliant Gigabit Media Independent Interface (GMII) connecting the MAC and internal PHY units. The second mode of operation incorporates the use of an internal Ten-Bit Interface (TBI), which connects the MAC to an internal Serial/De-serializing device (SerDes). In standard applications, the 82545EM/GM and 82546EB/GB are designed in one of the two modes of operation. The third mode of operation exposes the internal TBI interface on external pins, bypassing the internal SerDes.

It might be desirable to create a design application such that the controller can dynamically switch, via software, between internal PHY mode and internal SerDes mode. After research and testing, Intel has identified a mechanism that appears to support such an application. It is important to note that though Intel believes to have identified a mechanism, as this is not a pre-production design-target or feature of the products, all responsibility for validating and supporting any implementation of such an application is considered to be customer responsibility. Additionally, for the purpose of this document, discussions surrounding the internal SerDes mode of operation also applies to external TBI mode of operation. The exception is the Link_Mode indication bits and the pin descriptions discussed later in this application note.

It is the intention of this document to be used as a guide, in conjunction with current 82545EM/GM and 82546EB/GB design documentation, describing how to develop a design capable of switching from internal PHY mode to internal SerDes mode without requiring a system level reset or power cycle. This document refers to signal definitions and circuit connections described in the following documents:
• Intel 82546EB Dual Port Gigabit Ethernet Controller Networking Silicon Datasheet
• Intel 82546GB Dual Port Gigabit Ethernet Controller Networking Silicon Datasheet

Read the full Intel® 82545/82546 GbE Controllers Dynamically Changing Link Modes application note.

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