ICS1893AGLF datasheet(16/135 Pages) ICST

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ICS1893AG, Rev A 04/14/05

April, 2005

Chapter 4 Overview of the ICS1893AG

ICS1893AG Data Sheet - Preliminary

4.1 100Base-TX Operation

During 100Base-TX data transmission, the ICS1893AG accepts packets from a MAC and inserts

Start-of-Stream Delimiters (SSDs) and End-of-Stream Delimiters (ESDs) into the data stream. The

ICS1893AG encapsulates each MAC/repeater frame, including the preamble, with an SSD and an ESD. As

per the ISO/IEC Standard, the ICS1893AG replaces the first octet of each MAC preamble with an SSD and

appends an ESD to the end of each MAC/repeater frame.

When receiving data from the medium, the ICS1893AG removes each SSD and replaces it with the

pre-defined preamble pattern before presenting the nibbles to its MAC Interface. When the ICS1893AG

encounters an ESD in the received data stream, signifying the end of the frame, it ends the presentation of

nibbles to its MAC Interface. Therefore, the local MAC receives an unaltered copy of the transmitted frame

sent by the remote MAC/repeater.

During periods when MAC frames are being neither transmitted nor received, the ICS1893AG signals and

detects the IDLE condition on the Link Segment. In the 100Base-TX mode, the ICS1893AG transmit

channel sends a continuous stream of scrambled ones to signify the IDLE condition. Similarly, the

ICS1893AG receive channel continually monitors its data stream and looks for a pattern of scrambled

ones. The results of this signaling and monitoring provide the ICS1893AG with the means to establish the

integrity of the Link Segment between itself and its remote link partner and inform its Station Management

Entity (STA) of the link status.

For 100M data transmission, the ICS1893AG MAC Interface is configured to provide a 100M Media

Independent Interface (MII).

4.2 10Base-T Operation

During 10Base-T data transmission, the ICS1893AG inserts only the IDL delimiter into the data stream.

The ICS1893AG appends the IDL delimiter to the end of each MAC frame. However, since the 10Base-T

preamble already has a Start-of-Frame delimiter (SFD), it is not required that the ICS1893AG insert an

SSD-like delimiter.

When receiving data from the medium (such as a twisted-pair cable), the ICS1893AG uses the preamble to

synchronize its receive clock. When the ICS1893AG receive clock establishes lock, it presents the

preamble nibbles to its MAC Interface. The 10M MAC Interface can be configured as either a 10M MII

Interface.

In 10M operations, during periods when MAC frames are being neither transmitted nor received, the

ICS1893AG signals and detects Normal Link Pulses. This action allows the integrity of the Link Segment

with the remote link partner to be established and then reported to the ICS1893AG’s STA.

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