AutoNegotiation
5-11
based on a successful parallel detection to indicate a valid 802.3u
selector field. Software may determine that negotiation completed
through Parallel Detection by reading a zero in the
AutoNegotiate
Expansion Register (ANER) Address 0x06
bit 0 once the
Basic Mode
Status Register (BMSR) Address 0x01
bit 5 is set. If any condition other
than a single good link occurs, the parallel detect fault bit is set (bit 4,
register 0x06).
5.3.8 AutoNegotiation Restart
Once AutoNegotiation has completed, it may be restarted at any time by
setting bit 9 (Restart AutoNegotiation) of the
Basic Mode Register
(BMCR) Address 0x00
to 1. If the mode configured by a successful
AutoNegotiation loses a valid link, then the AutoNegotiation process
resumes and attempts 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,
causes the L80600 to halt any transmit data and link pulse activity until
the break_link_timer expires (approximately 1500 ms). Consequently, the
Link Partner goes into link fail and normal AutoNegotiation resumes. The
L80600 resumes AutoNegotiation after the break_link_timer has expired
by issuing FLP (Fast Link Pulse) bursts.
5.3.9 Enabling AutoNegotiation through Software
It is important to note that if the L80600 has been initialized at power-up
as a Non-AutoNegotiating device (forced technology), it is then required
that AutoNegotiation or re-AutoNegotiation be initiated through software.
Bit 12 (AutoNegotiation Enable) of the
Basic Mode Register (BMCR)
Address 0x00
must first be cleared and then set for any AutoNegotiation
function to take effect.
5.3.10 AutoNegotiation Complete Time
Completing parallel detection and AutoNegotiation takes approximately
2–3 seconds for 10/100 Mbits/s devices and 5–6 seconds for
1000 Mbits/s devices. In addition, completing AutoNegotiation with Next
Page should take approximately 2–3 seconds, depending on the number
of next pages sent.