Samsung KS8910, User Manual

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KS8910 100/10 Mbps ETHERNET TRANSCEIVER 100BASE-TX DIGITAL BLOCKS
4-9
Preliminary Spec. ver
1.4
PARALLEL AND SERIAL CONVERTERS
Serial Converter (Transmit Bits STM)
The Serial Converter receives a stream of 5-bit code-groups in parallel form from the Encoder and converts it into a
serial bit stream which is then forwarded to the PMA. The serial inversion takes place in the 125MHz clock domain.
The state diagram for the converter is shown in Figure 24-7 in the IEEE 802.3u standard.
Parallel Converter (Receive Bits State)
The Parallel Converter receives a serial bit stream from the PMA and coverts it into a stream of 5-bit code-groups in
parallel form which is then forwarded to the Decoder. Before the conversion can take place the Encode has to lock
to the incoming serial bit stream. The Encoder provides the Parallel Converter with an “align signal” after it has
discovered the Start-of-Stream Delimiter. The parallel conversion takes place in the 125MHz clock domain. The
state diagram for the converter is shown in Figure 24-10 in the IEEE 802.3u standard.
CARRIER SENSE
Carrier sense, CRS, is set active if either the Encoder is transmitting or if the Decoder is receiving or if both are
active at the same time. It is used by the MAC controller for frame reception or deferral of frame transmission.