ICS1893Y-10 Datasheet, PDF (18/150 Pages) –

ICS1893Y-10 Data Sheet - Release
Chapter 3 Overview of the ICS1893Y-10
3.1 100Base-TX Operation
During 100Base-TX data transmission, the ICS1893Y-10 accepts packets from a MAC/repeater and inserts
Start-of-Stream Delimiters (SSDs) and End-of-Stream Delimiters (ESDs) into the data stream. The
ICS1893Y-10 encapsulates each MAC/repeater frame, including the preamble, with an SSD and an ESD.
As per the ISO/IEC Standard, the ICS1893Y-10 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 ICS1893Y-10 removes each SSD and replaces it with the
pre-defined preamble pattern before presenting the nibbles to its MAC/Repeater Interface. When the
ICS1893Y-10 encounters an ESD in the received data stream, signifying the end of the frame, it ends the
presentation of nibbles to its MAC/Repeater Interface. Therefore, the local MAC/repeater 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 ICS1893Y-10 signals and
detects the IDLE condition on the Link Segment. In the 100Base-TX mode, the ICS1893Y-10 transmit
channel sends a continuous stream of scrambled ones to signify the IDLE condition. Similarly, the
ICS1893Y-10 receive channel continually monitors its data stream and looks for a pattern of scrambled
ones. The results of this signaling and monitoring provide the ICS1893Y-10 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 ICS1893Y-10 MAC/Repeater Interface can be configured to provide either
a 100M Media Independent Interface (MII) or a 100M Symbol Interface. With the Symbol Interface
configuration, the data stream bypasses the ICS1893Y-10 Physical Coding sublayer (PCS). In addition:
1. The ICS1893Y-10 shifts the responsibility of performing the 4B/5B translation to the MAC/repeater. As
a result, the requirement is for a 5-bit data path between the MAC/repeater and the ICS1893Y-10.
2. The latency through the ICS1893Y-10 is reduced. (The ICS1893Y-10 provides this 100M Symbol
Interface primarily for repeater applications for which latency is a critical performance parameter.)
3.2 10Base-T Operation
During 10Base-T data transmission, the ICS1893Y-10 inserts only the IDL delimiter into the data stream.
The ICS1893Y-10 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 ICS1893Y-10 insert an
SSD-like delimiter.
When receiving data from the medium (such as a twisted-pair cable), the ICS1893Y-10 uses the preamble
to synchronize its receive clock. When the ICS1893Y-10 receive clock establishes lock, it presents the
preamble nibbles to its MAC/Repeater Interface. The 10M MAC/Repeater Interface can be configured as
either a 10M MII, a 10M Serial Interface, or a Link Pulse Interface.
In 10M operations, during periods when MAC frames are being neither transmitted nor received, the
ICS1893Y-10 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 ICS1893Y-10’s STA.
ICS1893Y-10 Rev F 1/20/04
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
18
January, 2004