DP83849IFVSSLASHNOPB datasheet(33/105 Pages) TI1

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DP83849IF

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SNOSAX8D – JUNE 2009 – REVISED APRIL 2013

The Auto-Negotiation Expansion Register (ANER) indicates additional Auto-Negotiation status. The ANER

provides status on:

•

Whether or not a Parallel Detect Fault has occurred

•

Whether or not the Link Partner supports the Next Page function

•

Whether or not the DP83849IF supports the Next Page function

•

Whether or not the current page being exchanged by Auto-Negotiation has been received

•

Whether or not the Link Partner supports Auto-Negotiation

5.2.3

Auto-Negotiation Parallel Detection

The DP83849IF supports the Parallel Detection function as defined in the IEEE 802.3u specification.

Parallel Detection requires both the 10 Mb/s and 100 Mb/s receivers to monitor the receive signal and

report link status to the Auto-Negotiation function. Auto-Negotiation uses this information to configure the

correct technology in the event that the Link Partner does not support Auto-Negotiation but is transmitting

link signals that the 100BASE-TX or 10BASE-T PMAs recognize as valid link signals.

If the DP83849IF completes Auto-Negotiation as a result of Parallel Detection, bits 5 and 7 within the

ANLPAR register will be set to reflect the mode of operation present in the Link Partner. Note that bits 4:0

of the ANLPAR will also be set to 00001 based on a successful parallel detection to indicate a valid 802.3

selector field. Software may determine that negotiation completed via Parallel Detection by reading a zero

in the Link Partner Auto-Negotiation Able bit once the Auto-Negotiation Complete bit is set. If configured

for parallel detect mode and any condition other than a single good link occurs then the parallel detect

fault bit will be set.

5.2.4

Auto-Negotiation Restart

Once Auto-Negotiation has completed, it may be restarted at any time by setting bit 9 (Restart Auto-

Negotiation) of the BMCR to one. If the mode configured by a successful Auto-Negotiation loses a valid

link, then the Auto-Negotiation process will resume and attempt to determine the configuration for the link.

This function ensures that a valid configuration is maintained if the cable becomes disconnected.

A renegotiation request from any entity, such as a management agent, will cause the DP83849IF to halt

any transmit data and link pulse activity until the break_link_timer expires (~1500 ms). Consequently, the

Link Partner will go into link fail and normal Auto-Negotiation resumes. The DP83849IF will resume Auto-

Negotiation after the break_link_timer has expired by issuing FLP (Fast Link Pulse) bursts.

5.2.5

Enabling Auto-Negotiation via Software

It is important to note that if the DP83849IF has been initialized upon power-up as a non-auto-negotiating

device (forced technology), and it is then required that Auto-Negotiation or re-Auto-Negotiation be initiated

via software, bit 12 (Auto-Negotiation Enable) of the Basic Mode Control Register (BMCR) must first be

cleared and then set for any Auto-Negotiation function to take effect.

5.2.6

Auto-Negotiation Complete Time

Parallel detection and Auto-Negotiation take approximately 2-3 seconds to complete. In addition, Auto-

Negotiation with next page should take approximately 2-3 seconds to complete, depending on the number

of next pages sent.

Refer to Clause 28 of the IEEE 802.3u standard for a full description of the individual timers related to

Auto-Negotiation.

Configuration

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