DM9013 datasheet(64/75 Pages) DAVICOM

64 / 75 page

DM9013

3-port switch with Processor Interface

Preliminary datasheet

DM9013-15-DS-P03

April 9, 2009

9.4.2.8 Code Group Alignment

The Code Group Alignment block receives un-aligned

5B data from the descrambler and converts it into 5B

code group data. Code Group Alignment occurs after

the J/K is detected and subsequent data is aligned on

a fixed boundary.

9.4.2.9 4B5B Decoder

The 4B5B Decoder functions as a look-up table that

translates incoming 5B code groups into 4B (Nibble)

data. When receiving a frame, the first 2 5-bit code

groups receive the start-of-frame delimiter (J/K

symbols). The J/K symbol pair is stripped and two

nibbles of preamble pattern are substituted. The last

two code groups are the end-of-frame delimiter (T/R

Symbols).

The T/R symbol pair is also stripped from the nibble,

presented to the Reconciliation layer.

9.4.3 10Base-T Operation

The 10Base-T transceiver is IEEE 802.3u compliant.

When the DM9013 is operating in 10Base-T mode,

the coding scheme is Manchester. Data processed

for transmit is presented in nibble format, converted

to a serial bit stream, then the Manchester encoded.

When receiving, the bit stream, encoded by the

Manchester, is decoded and converted into nibble

format.

9.4.4 Collision Detection

For half-duplex operation, a collision is detected

when the transmit and receive channels are active

simultaneously. Collision detection is disabled in full

duplex operation.

9.4.5 Carrier Sense

Carrier Sense (CRS) is asserted in half-duplex

operation during transmission or reception of data.

During full-duplex mode, CRS is asserted only during

receive operations.

9.4.6 Auto-Negotiation

The objective of Auto-negotiation is to provide a

means to exchange information between linked

devices and to automatically configure both devices

to take maximum advantage of their abilities. It is

important to note that Auto-negotiation does not test

the characteristics of the linked segment. The

Auto-Negotiation function provides a means for a

device to advertise supported modes of operation to

a remote link partner, acknowledge the receipt and

understanding of common modes of operation, and to

reject un-shared modes of operation. This allows

devices on both ends of a segment to establish a link

at the best common mode of operation. If more than

one common mode exists between the two devices, a

mechanism is provided to allow the devices to

resolve to a single mode of operation using a

predetermined priority resolution function.

Auto-negotiation also provides a parallel detection

function for devices that do not support the

Auto-negotiation feature. During Parallel detection

there is no exchange of information of configuration.

Instead, the receive signal is examined. If it is

discovered that the signal matches a technology,

which the receiving device supports, a connection will

be automatically established using that technology.

This allows devices not to support Auto-negotiation

but support a common mode of operation to establish

a link.

DM9013 Datasheet(PDF) 64 Page - Davicom Semiconductor, Inc.

DM9013 Datasheet(HTML) 64 Page - Davicom Semiconductor, Inc.

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