CX82100 Home Network Processor Data Sheet
7.3
EMAC Functional Features
The EMAC block supports the MAC sublayer of the IEEE 802.3 and allows it to be
connected to an IEEE 802.3 10/100 Mbps (100BASE-T and 10BASE-T) MII compatible
EPHY device. The EMAC block supports the following features:
•
For frame transmission
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Accepts data from host and constructs a frame
Presents nibble data stream to the EPHY
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For frame reception
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Receives nibble data stream from the EPHY
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Presents to the host frames that are either broadcast/multicast frames or directly
addressed to the local station
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Discards or passes to the host all frames not addressed to it (programmable)
Defers transmission whenever the medium is busy
Delays transmission of frame for specified interframe gap (IFG) period
Appends preamble, SFD, FCS to frames, and inserts PAD field for frames
whose data length is less than minFrameSize
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Halts transmission when collision is detected
Enforces collision to ensure propagation throughout network by sending jam
message
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Schedules retransmission after a collision until attemptLimit is reached
Checks received frames for transmission errors by way of FCS
Discards received frames that are less than minFrameSize.
Removes preamble and SFD. FCS and pad field (if necessary) from received
frames are passed along.
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IEEE 802.3u MII Physical Layer Interface
Full-duplex or half-duplex operation
Normal and internal loopback mode
Linked list transmit data structures for scatter/gather support.
Programmable data padding and FCS capability
Address filtering (promiscuous, perfect, inverse and hash filtering)
Programmable IFG
Generates signals for software to maintain MIB (Management Information
Base) status in software
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Management Data Interface (MDI) to an MII compliant EPHY
qword (64-bit) interface to the DMA controller
In half-duplex mode, the HNP checks the line condition before starting to transmit. If the
condition is clear, it starts transmitting (after IFG). Transmit enable (EMx_TXEN) asserts
and data is transferred through the MII port.
7-4
Conexant Proprietary and Confidential Information
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CONEXANT [ CONEXANT SYSTEMS, INC ]
