LAN8810I-AKZE Datasheet, PDF (37/100 Pages) Microchip Technology – GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support

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3.9.6.4
3.9.6.5
GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Failure to complete the auto-negotiation process is reported through the following status bits:
 Parallel Detection Fault reported in the Auto Negotiation Expansion Register while operating in
10BASE-T or 100BASE-TX modes.
 Master/Slave Configuration Fault reported in the Master/Slave Status Register while operating in
1000BASE-T mode.
A fault occurs if the Master/Slave configuration conditions do not allow master/slave resolution, as
defined in the Master/Slave Manual Config Enable and Master/Slave Manual Config Value bits in the
Master/Slave Control Register of the local and remote link partners.
1000BASE-T
For 1000BASE-T links, the device and its link partner enter a training phase after completion of the
auto-negotiation process. The links exchange idle symbols and use the information obtained from
receiving this signal to set their adaptive filter coefficients.
These coefficients are used in the receiver to equalize the incoming signal, as well as eliminate signal
impairments such as echo and cross-talk. Each side indicates completion of the training phase to its
link partner by changing the encoding of the idle-symbols it transmits.
The link is established after both sides indicate completion of the training phase. Each side continues
to send idle symbols whenever it has no data to transmit. The link is maintained as long as valid idle,
data, or carrier extension symbols are received.
Status of both local and remote receivers is reported in the Local Receiver Status and Remote
Receiver Status bits of the Master/Slave Status Register.
The device also provides an advanced Auto Link Breaker feature (only for 1000BASE-T links). Using
this feature, the link can be taken down if the bit error rate (BER) exceeds the threshold defined in
Link Break Threshold field of the Link Control Register. The error counting occurs during the idle time
for a period commensurate with the specified BER. The Auto Link Breaker feature is enabled via the
Link Break Enable bit of the Link Control Register.
100BASE-TX
For 100BASE-TX links, the device and its link partner begin transmitting idle symbols after completion
of the auto-negotiation process. Each side continues sending idle symbols whenever it has no data to
transmit. The link is maintained as long as valid idle symbols or data are received.
10BASE-T
For 10BASE-T links, the device and its link partner begin exchanging normal link pulses (NLPs) after
completion of the auto-negotiation process. The device transmits an NLP every 16ms and expects to
receive an NLP every 8 to 24ms. A link is maintained as long as NLPs are received.
Taking Down a Link
The device takes down an established link when the required conditions are no longer met. When a
link is down, data transmission stops. For 10BASE-T links, the link is taken down after NLPs are no
longer received. For 100BASE-TX and 1000BASE-T links, the link is taken down after valid idle codes
are no longer received.
After a link is down, the device does the following:
 If auto-negotiation is enabled, the device re-enters the auto-negotiation phase and begins
transmitting FLPs
 If auto-negotiation is not enabled, the device transmits NLPs in 10BASE-T mode, and MLT-3s in
100BASE-TX mode.
SMSC LAN8810/LAN8810i
37
DATASHEET
Revision 1.0 (02-06-13)