Data Sheet

Interconnects—Ethernet Controller I210

Note: In internal PHY, SGMII, 1000BASE-BX and 1000BASE-KX connections, energy detect source is

always internal and value of CONNSW.ENRGSRC bit should be 0b. The CTRL.ILOS bit also

inverts the internal link-up input that provides link status indication and thus should be set to

0b for proper operation.

3.7.4.1.2 MAC Link Speed

SerDes/1000BASE-BX operation is only defined for 1000 Mb/s operation. Other link speeds are not

supported. When configured for the SerDes interface, the MAC speed-determination function is disabled

and the Device Status register bits (STATUS.SPEED) indicate a value of 10b for 1000 Mb/s.

3.7.4.1.3 SerDes/1000BASE-BX Mode Auto-Negotiation

In SerDes/1000BASE-BX mode, after power up or the I210 reset via PE_RST_N, the I210 initiates

IEEE802.3 clause 37 auto-negotiation based on the default settings in the device control and transmit

configuration or PCS Link Control Word registers, as well as settings read from the Flash. If enabled in

the Flash, the I210 immediately performs auto-negotiation.

TBI mode auto-negotiation, as defined in clause 37 of the IEEE 802.3z standard, provides a protocol for

two devices to advertise and negotiate a common operational mode across a GbE link. The I210 fully

supports the IEEE 802.3z auto-negotiation function when using the on-chip PCS and internal SerDes.

TBI mode auto-negotiation is used to determine the following information:

• Duplex resolution (even though the I210 MAC only supports full-duplex in SerDes/1000BASE-BX

mode).

• Flow control configuration.

Note: Since speed for SerDes/1000BASE-BX modes is fixed at 1000 Mb/s, speed settings in the

Device Control register are unaffected by the auto-negotiation process.

Note: Auto-negotiation can be initiated at power up or by asserting PE_RST_N and enabling specific

bits in the Flash.

The auto-negotiation process is accomplished by the exchange of /C/ ordered sets that contain the

capabilities defined in the PCS_ANADV register in the 3rd and 4th symbols of the ordered sets. Next

page are supported using the PCS_NPTX_AN register.

Bits FD and LU in the Device Status (STATUS) register, and bits in the PCS_LSTS register provide status

information regarding the negotiated link.

Auto-negotiation can be initiated by the following:

• PCS_LCTL.AN_ENABLE transition from 0b to 1b

• Receipt of /C/ ordered set during normal operation

• Receipt of a different value of the /C/ ordered set during the negotiation process

• Transition from loss of synchronization to synchronized state (if AN_ENABLE is set).

• PCS_LCTL.AN_RESTART transition from 0b to 1b

Resolution of the negotiated link determines device operation with respect to flow control capability and

duplex settings. These negotiated capabilities override advertised and software-controlled device

configuration.