ETHERNET CONTROLLER
S3C4510B
MAC FUNCTION BLOCKS
The major function blocks of the ethernet controller¢s MAC layer are described in Table 7-1 and Figure 7-1.
Table 7-1. MAC Function Block Descriptions
Function Block
Description
Media Independent
Interface (MII)
The interface between the physical layer and the transmit and receive blocks.
Transmit block
Moves the outgoing data from the transmit buffer to the MII. The transmit block
includes circuits for generating the CRC, checking parity, and generating
preamble or jam. The transmit block also has timers for back-off after collision
and for the interframe gap the follows a transmission.
Receive block
Accepts incoming data from the MII and stores it in the receive FIFO. The
receive block has logic for computing and checking the CRC value, generating
parity for data from the MII, and checking minimum and maximum packet
lengths. The receive block also has a content addressable memory (CAM) block
which provides for address lookup, and for acceptance or rejection for packets
based on their destination address.
Flow control block
Recognizes MAC control packets and supports the pause operation for full-duplex
links. The flow control block also supports generation of pause packets, and
provides timers and counters for pause control.
MAC control (command)
and status registers
Controls programmable options, including the enabling or disabling of signals
which notify the system when conditions occur. The status registers hold
information for error handling software, and the error counters accumulate
statistical information for network management software.
Loop-back circuit
Provides for MAC-layer testing in isolation from the MII and physical layer.
7-4
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