Intel PCI User Manual

13

Note: Refer to the Extended Device Control Register (bits 23:22) for mode selection (see 

The link can be configured by several methods. Software can force the link setting to Auto-
Negotiation by setting either the MAC in TBI

 

mode (internal SerDes for the 82546GB/EB and 

82545GM/EM), or the PHY in internal PHY mode.

The speed of the link in internal PHY mode can be determined by several methods:

•

Auto speed detection based on the receive clock signal generated by the PHY.

•

Detection of the PHY link speed indication.

•

Software forcing the configuration of link speed.

The Ethernet controller provides a full high-performance, integrated transceiver for 10/100/

1000 Mb/s data communication. The physical layer (PHY) blocks are 802.3 compliant and capable 

of operating in half-duplex or full-duplex modes.

Highlights of the PHY blocks are as follows:

•

Data stream serializers and encoders. Encoding techniques include Manchester, 4B/5B and 

4D/PAM5. These blocks also perform data scrambling for 100/1000 Mb/s transmission as a 

technique to minimize radiated Electromagnetic Interference (EMI).

•

A multi-mode transmit digital to analog converter, which produces filtered waveforms 

appropriate for the 10BASE-T, 100BASE-TX or 1000BASE-T Ethernet standards.

•

Receiver Analog-to-Digital Converter (ADC). The ADC uses a 125 MHz sampling rate.

•

Receiver decoders. These blocks perform the inverse operations of serializers, encoders and 

scramblers.

•

Active hybrid and echo canceller blocks. The active hybrid and echo canceller blocks reduce 
the echo effect of transmitting and receiving simultaneously on the same analog pairs.

•

NEXT canceller. This unit removes high frequency Near End Crosstalk induced among 

adjacent signal pairs.

•

Additional wave shaping and slew rate control circuitry to reduce EMI.

Because the Ethernet controller is IEEE-compliant, the PHY blocks communicate with the MAC 

blocks through an internal GMII/MII bus operating at clock speeds of 2.5 MHz up to 125 MHz.

The Ethernet controller also uses an IEEE-compliant internal Management Data interface to 
communicate control and status information to the PHY.

The PCI/PCI-X Family of Gigabit Ethernet Controllers provide a four-wire direct interface to a 
serial EEPROM device such as the 93C46 or compatible for storing product configuration 

information. Several words of the data stored in the EEPROM are automatically accessed by the 

Ethernet controller, after reset, to provide pre-boot configuration data to the Ethernet controller 
before it is accessible by the host software. The remainder of the stored information is accessed by 

various software modules to report product configuration, serial number and other parameters.