Altera Stratix GX Guide de l'utilisateur télécharger pdf (Page 155)

Altera Corporation 6–1

January 2005

6. GigE Mode

Introduction

The Gigabit Ethernet (GigE) mode in Stratix

GX devices supports a

subset of the IEEE GigE standard. Stratix GX devices have Physical

Coding Sub-layer (PCS) functions and Physical Medium Attachment

(PMA) functions as Hard Intellectual Property (IP).

Stratix GX devices provide the following GigE features:

■ Serial data rate of 1.25 Gigabits per second

■ Input clock reference range of 62.5 to 625 MHz (these values are the

minimum and maximum for an input reference clock with a data rate

of 1.25 Gbps and an 8-bit data width)

■ Parallel interface width of 8 bits

■ 8B/10B encoding decoder

■ Word aligner supports 10-bit code groups

■ Rate compensation or elastic buffer

■ Gigabit Media Independent Interface (GMII) to PCS code conversion

on transmit

The GMII is an intermediate or parallel interface that connects the PCS

sub-layer with the media access control (MAC) in a system that supports

GigE mode. The GigE physical layer is divided into three sub-layers: the

PCS, the PMA, and the physical medium dependent (PMD) layers. If you

implement a GMII-compliant interface, that interface offers data rates up

to 1,000 Mbps at either half- or full-duplex modes.

The PCS provides synchronization, encoding, decoding, and rate

matching services to the MAC. The PCS also provides autonegotiation to

the network to negotiate speeds, carrier-detect signals, and

collision-detect signals.

The PMA sublayer provides the PCS with a media-independent interface

that a variety of serial physical media can connect to. This sublayer

handles the serialization and deserialization of the data.

The PMD sublayer defines the physical attachments, such as connectors

for different media types.

Figure 6–1 shows the positioning of these layers.

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Altera Stratix GX Guide de l'utilisateur Page 155