Technical data

FEFI consists of a modification to the IDLE code patterns. In this mode, every 16 IDLE code groups

are followed by a data-0 code group. If the PHY detects a FEFI pattern in its receive stream, it de-

asserts its link status and transmits only IDLE patterns (not FEFI) on its transmit stream.

A full description of the Far End Fault Function is given in Section 24.3.2.1 in the IEEE 802.3 standard.

1.3.4 Auto Negotiation

The objective of the Auto-Negotiation function is to provide the means to exchange information

between two devices that share a link segment and to automatically configure both devices to take

maximum advantage of their abilities.

The auto-negotiation protocol is a purely physical layer activity and proceeds independently of the

MAC controller. The auto-negotiation function sends fast link pulse (FLP) bursts for exchanging

information with its link partner. A FLP burst consists of 33 pulse positions. The 17 odd-numbered

pulse positions shall contain a link pulse and represent clock information. The 16 even-numbered

pulse positions represent data information. The data transmitted by an FLP burst is known as a "Link

Code Word". These are fully defined in clause 28 of the IEEE 802.3 specification.

This core supports auto-negotiation and implements the “Base page”, defined by IEEE 802.3. It

also supports the optional “Next page” function to get the remote fault number code.

(1) Parallel detection

The parallel detection function allows detection of Link Partners that support 100BASE-TX and/or

10BASE-T, but do not support Auto-Negotiation. The PHY is able to determine the speed of the link

based on either 100M MLT-3 symbols or 10M Normal Link Pulses. If the PHY detects either mode, it

automatically reverts to the corresponding operating mode. In this case the link is presumed to be half

duplex.

If a link is established via parallel detection, then Bit 0 of the Auto-Negotiation Expansion register is

cleared to indicate that the link partner is not capable of auto-negotiation. The controller has access to

this information via the management interface. If a fault occurs during parallel detection, bit 4 of the

Auto-Negotiation Expansion register is set.

The Auto-Negotiation Link Partner Ability register is used to store the link partner ability information,

which is coded in the received FLPs. If the link partner is not auto-negotiation capable, then the Auto-

Negotiation Link Partner Ability register is updated after completion of parallel detection to reflect the

speed capabilities of the link partner.

(2) Re-negotiation

Auto-negotiation is started by one of the following events:

<1> H/W reset

<2> S/W reset

<3> setting the Auto-Negotiation Enable bit in the Basic Control register from low to high

When auto-negotiation is enabled, it is re-started by one of the following events:

<1> Link status is down.

<2> Setting the Auto-Negotiation Restart bit in the Basic Control register to high.

Technical data subject to change Version 1.0.0