Appendix B: Auto Negotiation
10/100/1000Mbps Copper Ethernet Auto Negotiation
200 SmartBits System Reference
• Advertisement Register (Register 4). This read/write register defines the capabilities
of the local interface for advertisement to the remote interface (also known as the Link
Partner; see below).
• Link Partner Register (Register 5). This read-only register stores information on the
capabilities of the communicating interface, as detected through the auto negotiation
protocol.
• 1000BASE-T2 Control Register (Register 9) (Copper Gigabit Only).Thisregister
sets control and management functions, such as the master/slave relationship of the
communicating PHYs, for 1000BASE-T2 copper Gigabit Ethernet interfaces.
• 1000BASE-T2 Status Register (Register 10) (Copper Gigabit Only). This read-
only register stores status information on PHY master/slave configuration, receiver
status, and Idle Error count for 1000BASE-T2 copper Gigabit Ethernet interfaces.
The PHY also conducts the auto negotiation protocol that exchanges the capability
information between the interfaces. Once both interfaces know each other’s capabilities,
the protocol selects the highest possible “common” mode of operation. Typically, other
program logic for the device or interface then adapts its general operating characteristics
to the characteristics selected through the auto negotiation process.
Note: The same MII register (Register 4) that advertises speed and duplex for auto
negotiation advertises a port's flow-control capability. Thus, the bit for flow control is set
at the same time as the bits for the speed/duplex options.
To Next Page
Loading...