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160 Software Developer’s Manual
Ethernet Interface
The following section describes the link configuration process in the Internal Serdes for the
82546GB/EB and 82545GM/EM (TBI mode for the 82544GC/EI) and internal PHY modes.
8.6.1 Link Configuration in Internal Serdes/TBI Mode
1
Internal Serdes for the 82546GB/EB and 82545GM/EM (TBI for the 82544GC/EI) Mode link
configuration can be performed via the on-chip PCS function in the Ethernet controller. The
hardware supports both hardware and software Auto-Negotiation methods for determining the link
configuration, as well as allowing for manual configuration to force the link.
Hardware Auto-Negotiation is the preferred method.
8.6.1.1 Link Speed
Internal Serdes for the 82546GB/EB and 82545GM/EM (TBI for the 82544GC/EI) Mode is only
defined for 1000 Mb/s operation. Other link speeds are not supported.
When the
82546GB/EB and 82545GM/EM is in internal Serdes mode, the speed determination
function is disabled and the Device Status register bits (STATUS.SPEED) bits indicate a value of
10b for 1000 Mb/s.
For the
82544GC/EI, when the TBI_MODE input is asserted for TBI mode, the speed
determination function is disabled and the Device Status register bits (STATUS.SPEED) bits
indicate a value of 10b for 1000 Mb/s.
8.6.1.2 Auto-Negotiation
At power up, or Ethernet controller reset via the RST# input, it initiates Auto-Negotiation based on
the default settings in the Device Control and Transmit Configuration Word registers, as well as
settings read from the EEPROM. If enabled in the EEPROM, the Ethernet controller immediately
performs Auto-Negotiation.
TBI Mode Auto-Negotiation, as defined in clause 37 of the IEEE 802.3z standard, provides a
protocol for two Ethernet controllers to advertise and negotiate a common operational mode across
a Gigabit Ethernet link. The Ethernet controller fully supports the IEEE 802.3z Auto-Negotiation
function when using the internal Serdes mode for the
82546GB/EB and 82545GM/EM or when
using the TBI and on-chip PCS for the
82544GC/EI.
TBI Mode Auto-Negotiation is used to determine the following information:
• Duplex resolution
• Flow control configuration
Speed for Internal Serdes mode (TBI mode for the
82544GC/EI) is fixed at 1000 Mb/s, so speed
settings in the Device Control register are unaffected by the Auto-Negotiation process.
There are two implementations accessible in the design:
1. A full hardware Auto-Negotiation implementation that does not require software intervention
in order to successfully reach a negotiated link configuration.
2. Software driven negotiation.
1. TBI mode for the 82544GC/EI.