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MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
11-1
Chapter 11
Ethernet Module
This chapter begins with a feature-set overview, a functional block diagram, and transceiver connection
information for both MII and seven-wire serial interfaces. The chapter concludes with detailed
descriptions of operation and the programming model.
11.1
Overview
The MCF5272’s integrated fast Ethernet media access controller (MAC) performs the full set of IEEE
802.3/Ethernet CSMA/CD media access control and channel interface functions. It requires an external
interface adaptor and transceiver function to complete the interface to the media.
11.1.1
Features
The fast Ethernet controller (FEC) incorporates the following features:
•
Full compliance with the IEEE 802.3 standard
•
Support for three different physical interfaces:
— 100 Mbps 802.3 media independent interface (MII)
— 10 Mbps 802.3 MII
— 10 Mbps seven-wire interface
•
Half-duplex 100-Mbps operation at system clock frequency Š 50 MHz
•
448 bytes total on-chip transmit and receive FIFO memory to support a range of bus latencies
Note: the total FIFO size is 448 bytes. It is not intended to hold entire frames but only to
compensate for external bus latency. The FIFO can be partitioned on any 32-bit boundary between
receive and transmit, for example, 32 x 56 receive and 32 x 56 transmit.
•
Retransmission from transmit FIFO following a collision, no processor bus used
•
Automatic internal flushing of the receive FIFO for runts and collisions with no processor bus use
11.2
Module Operation
The FEC is implemented using a combination of hardware and microcode.
block diagram of this module.