ADM7008
Function Description
High Z
Low Z
Comparator with positive threshold voltage in TRXANA, then the pulse
will pass to PHYDIG.
Comparator with negative threshold voltage in TRXANA, then the pulse
will pass to PHYDIG.
3.1.18 Auto Negotiation
The Auto Negotiation function provides a mechanism for exchanging configuration
information between two ends of a link segment and automatically selecting the highest
performance mode of operation supported by both devices. Fast Link Pulse (FLP) Bursts
provide the signaling used to communicate auto negotiation abilities between two devices
at each end of a link segment. For further detail regarding auto negotiation, refer to
Clause 28 of the IEEE 802.3u specification. The ADM7008 supports four different
Ethernet protocols, so the inclusion of auto negotiation ensures that the highest
performance protocol will be selected based on the ability of the link partner.
The auto negotiation function within the ADM7008 can be controlled either by internal
register access or by the use of configuration pins are sampled. If disabled, auto
negotiation will not occur until software enables bit 12 in register 0. If auto negotiation is
enabled, the negotiation process will commence immediately.
When auto negotiation is enabled, the ADM7008 transmits the abilities programmed into
the auto negotiation advertisement register at address 04h via FLP bursts. Any
combination of 10 Mbits/s, 100 Mbits/s, half duplex and full duplex modes may be
selected. Auto negotiation controls the exchange of configuration information. Upon
successfully auto negotiation, the abilities reported by the link partner are stored in the
auto negotiation link partner ability register at address 05h.
The contents of the “auto negotiation link partner ability register” are used to
automatically configure to the highest performance protocol between the local and far-
end nodes. Software can determine which mode has been configured by auto negotiation
ADMtek Inc.
3-12
ETC [ ETC ]
