Technical data

(3) Priority Resolution

If two Ethernet communication partners negotiate their capabilities, there are four possible matches of

the technology abilities. In the order of priority these are:

• 100M full Duplex (highest priority)

• 100M Half Duplex

• 10M full Duplex

• 10M Half Duplex (lowest priority)

Since two devices (local device and remote device) may have multiple abilities in common, a prioritiza-

tion scheme exists to ensure that the highest common denominator ability is chosen. Full duplex solu-

tions are always higher in priority than their half duplex counterparts. 10BASE-T is the lowest common

denominator and therefore has the lowest priority.

If a link is formed via parallel detection, then the Link Partner Auto-negotiation Able bit in 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, the Parallel Detection Fault bit in the same register is set. The Auto-

Negotiation Link Partner Ability register 5 is used to store the link partner’s ability information, which

was decoded from 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 capability of the link partner.

(4) Next Page function

Additional information, exceeding that required by base page exchange, is also sent via “Next Pages”;

this PHY supports the optional “Next page” function. Next page exchange occurs after the base page

has been exchanged. Next page exchange consists of using the normal Auto-Negotiation arbitration

process to send next page messages. Two kinds of message encodings are defined: Message Pages,

which contain predefined 11 bit codes, and unformatted pages .

Next page transmission ends when both ends of a link segment set their Next Page bits to logic zero,

indicating that neither has anything additional to transmit. It is possible for one device to have more

pages to transmit than the other device. Once a device has completed transmission of its next page

information, it shall transmit message pages with Null message codes and the NP bit set to logic zero

while its link partner continues to transmit valid next pages.

Devices, that are able of auto-negotiation, shall recognize reception of message pages with Null mes-

sage codes as the end of its link partner’s next page information. The default value of the next page

support is disable (Next Page bit in Auto-Negotiation Advertisement register). To enable next page

support, the Next Page bit should be set to 1

. Auto-Negotiation should be restarted and the message

code to be transmitted to the remote link partner should be written to bit(10:0) of the Auto-Negotiation

Next Page Transmit register .

(5) Disabling Auto-Negotiation

Auto-negotiation can be disabled by setting the Auto-Negotiation Enable bit in the Basic Control regis-

ter. When Auto-negotiation is disabled, the speed and duplex mode settings are configured via the

serial management interface.

Technical data subject to change Version 1.0.0