GBE-PCS-PM-U1

The 1000BASE-X physical layer, also referred to as the Gigabit Ethernet (GbE) physical layer, consists of three

major blocks, the Physical Coding Sublayer (PCS), the Physical Medium Attachment sublayer (PMA), and the

Physical Medium Dependent sublayer (PMD). The LatticeECP2M™ embedded SERDES/PCS performs the PMA

function, and portions of the PMD and PCS functions, including link serialization/deserialization, code-group align-

ment, clock tolerance compensation buffering, and 8b10b encoding/decoding. However, the embedded SER-

DES/PCS does not provide all necessary functions for implementing a complete GbE physical layer solution. That’s

where the GbE PCS IP core comes in. The IP core provides the additional functions required to fully implement the

PCS functions of the GbE physical layer. These additional functions include a transmit state machine, a receive

state machine, and auto-negotiation.

This document describes the IP core’s operation and provides instructions for generating the core through

• Parallel signal interface for control and status management

example of how this IP core may be used in implementing a gigabit ethernet physical layer is shown in Figure 2.

Figure 1. GbE PCS IP Core Block Diagram

Figure 2. Typical GbE Physical Layer Implementation

tion. The state machine’s main purpose is to convert GMII data frames into code groups. A typical timing diagram

for this circuit block is shown below. Note that the state machine in this IP core does not fully implement the conver-

sion to 10-bit code groups as specified in the 802.3 specification. Instead, partial conversion to 8-bit code groups is

performed. A separate encoder (located in the LatticeECP2M embedded SERDES/PCS block) completes the full

conversion to 10-bit code groups.

Figure 3. Typical Transmit Timing Diagram

tion. The state machine’s main purpose is to convert code groups into GMII data frames. A typical timing diagram

for this circuit block is shown below. Note that the state machine in this IP core does not fully implement the conver-

sion from 10-bit code groups as specified in the 802.3 specification. Instead, partial conversion from 8-bit code

10-bit to 8-bit conversions.