MPC8540 datasheet(629/1302 Pages) FREESCALE

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Introduction

MPC8540 PowerQUICC III Integrated Host Processor Reference Manual, Rev. 1

Freescale Semiconductor

14-3

(SerDes) and vice versa. Synchronization is also performed for proper data decoding in this

sublayer. The PMA sits between the PCS and the PMD sublayers. For fiber medium

(1000BASEX) the interface on the PMD side of the PMA is a 1-bit 1250-MHz signal, while

on the PMA’s PCS side the interface is a 10-bit interface (TBI) at 125 MHz. The TBI is an

alternative to the GMII interface. If the TBI is used, the gigabit Ethernet controller must be

capable of performing the PCS function. For UTP medium, the PMD interface side of the

PMA consists of four pair of 62.5-MHz PAM5 encoded signals, while the PCS side

provides the 1250 Mbps input to a 8B1Q4 PCS.

•

PMD (physical medium dependent) sublayer—The PMD sublayer is responsible for signal

transmission. The typical PMD functionality includes amplifier, modulation, and wave

shaping. Different PMD devices may support different media.

•

MDI (medium-dependent interface) sublayer—MDI is a connector. It defines different

connector types for different physical media and PMD devices.

Figure 14-2 describes the different physical interface standards.

Figure 14-2. IEEE 802.3z and 802.3ab Physical Standards

Ethernet/IEEE 802.3 frames are based on the frame structure shown in Figure 14-3. The term

‘packet’ is sometimes used to refer to the frame plus the preamble and start frame delimiter (SFD).

Figure 14-3. Ethernet/IEEE 802.3 Frame Structure

Gigabit Media-Independent Interface (GMII) (optional)

1000BASEX PCS

8 bytes/10 bytes auto-negotiation

1000BaseLX

fiber optics

1000BaseSX

fiber optics

1000BaseCX

copper

MAC full-duplex and/or half-duplex

802.3ab

1000BaseT

PCS

1000BaseT

PMA

Shielded

copper cable

(25 m)

Multimode

fiber

(500 m)

Single-mode or

multimode fiber

(3 Km)

TBI

802.3z

Unshielded

twisted pair

(100 m)

Start frame

delimiter

Preamble

Data

Destination

address

Source

address

Type/

Length

6 bytes

1 byte

7 bytes

2 bytes

6 bytes

46–1500 bytes

4 bytes

Frame check

sequence

Frame length is 64–1518 bytes

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