Motorola MCF5282, MCF5281 user manual FEC Top-Level Functional Diagram, Pad

Models: MCF5282 MCF5281

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FEC Top-Level Functional Diagram

17.3 FEC Top-Level Functional Diagram

The block diagram of the FEC is shown below. The FEC is implemented with a combination of hardware and microcode. The off-chip (Ethernet) interfaces are compliant with industry and IEEE 802.3 standards.

 

SIF

 

 

 

 

 

 

Bus

 

 

 

 

 

Controller

 

 

 

 

 

 

 

CSR

RAM

 

FIFO

DMA

 

 

Controller

 

Descriptor

 

 

 

 

 

Controller

 

RAM I/F

 

 

(RISC +

 

 

 

 

 

microcode)

 

 

 

 

 

 

 

 

 

 

 

FEC Bus

 

MII

MIB

 

Transmit

Receive

 

 

 

 

 

 

 

Counters

 

 

 

 

MDO

 

 

 

 

 

 

MDEN

MDI

 

 

 

 

 

 

 

 

 

 

 

 

I/O

 

 

ETXEN

ETCLK

ERXCLK

 

PAD

 

 

ETXD[3:0] ECRS,ECOL

ERXDV

 

 

 

 

ETXER

 

ERXD[3:0]

 

 

 

 

 

 

ERXER

EMDIO EMDC

MII/7-WIRE DATA

OPTION

Figure 17-1. FEC Block Diagram

The descriptor controller is a RISC-based controller that provides the following functions in the FEC:

Initialization (those internal registers not initialized by the user or hardware)

High level control of the DMA channels (initiating DMA transfers)

Interpreting buffer descriptors

Address recognition for receive frames

Random number generation for transmit collision backoff timer

17-4

MCF5282 User’s Manual

MOTOROLA

Page 360
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Motorola MCF5282, MCF5281 user manual FEC Top-Level Functional Diagram, Pad