10/100 Non-PCI Ethernet Single Chip MAC + PHY
Datasheet
a.) Normal Link Pulse (NLP)
b.) Fast Link Pulse (FLP)
TPO±
TPO±
D0
D1
D2
D3
D14
D15
Clock
Clock
Data
Clock
Data
Clock
Data
Clock
Clock
Data
Clock
Data
Data
Figure 7.8 NLP VS. FLP Link Pulse
The AutoNegotiation algorithm is initiated by any of these events: (1) AutoNegotiation enabled, (2) a
device enters the Link Fail State, (3) AutoNegotiation Reset. Once a negotiation has been initiated,
the LAN91C111 first determines if the remote device has AutoNegotiation capability. If the remote
device is not AutoNegotiation capable and is just transmitting either a 10BASE-T or 100BASE-TX
signal, the LAN91C111 will sense that and place itself in the correct mode. If the LAN91C111 detects
FLP's from the remote device, then the remote device is determined to have AutoNegotiation capability
and the device then uses the contents of the Ml serial port AutoNegotiation Advertisement register and
FLP's to advertise its capabilities to a remote device. The remote device does the same, and the
capabilities read back from the remote device are stored in the PHY Ml serial port AutoNegotiation
Remote End Capability register. The LAN91C111 negotiation algorithm then matches it's capabilities
to the remote device's capabilities and determines what mode the device should be configured to
according to the priority resolution algorithm defined in IEEE 802.3 Clause 28. Once the negotiation
process is completed, the LAN91C111 then configures itself for either 10 or 100 Mbps mode and either
Full or Half Duplex modes (depending on the outcome of the negotiation process), and it switches to
either the 100BASETX or 10BASE-T link integrity algorithms (depending on which mode was enabled
by AutoNegotiation). Refer to IEEE 802.3 Clause 28 for more details.
AutoNegotiation Outcome Indication
The outcome or result of the AutoNegotiation process is stored in the speed detect and duplex detect
bits in the PHY MI serial port Status Output register.
AutoNegotiation Status
The status of the AutoNegotiation process can be monitored by reading the AutoNegotiation
acknowledgement bit in the Ml serial port Status register. The Ml serial port Status register contains
a single AutoNegotiation acknowledgement bit which indicates when an AutoNegotiation has been
initiated and successfully completed.
AutoNegotiation Enable
The AutoNegotiation algorithm can be enabled by setting both the ANEG bit in the MAC Receive/PHY
Control Register and the ANEG_EN bit in the MI PHY Register 0 (Control register). Clearing either of
these two bits will turn off AutoNegotiation mode. When the AutoNegotiation algorithm is enabled, the
Revision 1.8 (07-13-05)
SMSC LAN91C111-REV B
DATA4S8HEET
SMSC [ SMSC CORPORATION ]
