Motorola MPC8260 User Manual

MOTOROLA

Chapter 24.  SCC Ethernet Mode  

24-3

The following list summarizes the main features of the SCC in Ethernet mode:

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Performs MAC layer functions of Ethernet and IEEE 802.3

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Performs framing functions

Ñ Preamble generation and stripping

Ñ Destination address checking

Ñ CRC generation and checking

Ñ Automatically pads short frames on transmit

Ñ Framing error (dribbling bits) handling

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Full collision support

Ñ Enforces the collision (jamming)

Ñ Truncated binary exponential backoff algorithm for random wait

Ñ Two nonaggressive backoff modes

Ñ Automatic frame retransmission (until the attempt limit is reached)

Ñ Automatic discard of incoming collided frames

Ñ Delay transmission of new frames for speciÞed interframe gap

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Maximum 10 Mbps bit rate

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Optional full-duplex support

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Back-to-back frame reception

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Detection of receive frames that are too long

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Multibuffer data structure

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Supports 48-bit addresses in three modes

Ñ PhysicalÐOne 48-bit address recognized or 64-bin hash table for physical 

addresses

Ñ LogicalÐ64-bin group address hash table plus broadcast address checking

Ñ PromiscuousÐReceives all addresses, but discards frame if REJECT is asserted 

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External content-addressable memory (CAM) support on serial bus interfaces

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Up to eight parallel I/O pins can be sampled and appended to any frame

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Optional heartbeat indication

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Transmitter network management and diagnostics

Ñ Lost carrier sense

Ñ Underrun

Ñ Number of collisions exceeded the maximum allowed