DM9008C View Datasheet(PDF) - Davicom Semiconductor, Inc.
Part Name
Description
MFG CO.
'DM9008C' PDF : 52 Pages View PDF
DM9008C
Ethernet Controller with General Processor Interface
9.5 10Base-T Operation
The 10Base-T transceiver is IEEE 802.3u compliant.
When the DM9008C 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.
9.6 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.
9.7 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.
9.8 Auto-Negotiation
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.
The objective of Auto-negotiation is to provide a
Preliminary
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Version: DM9008C-13-DS-P01
January 15, 2008
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