ICS1893Y-10 Datasheet, PDF (55/150 Pages) –

ICS1893Y-10 - Release
Chapter 6 Functional Blocks
Note:
1. An ICS1893Y-10 receives ‘valid data’ when its Twisted-Pair Receiver phase-locked loop can acquire
lock and extract the receive clock from the incoming data stream for a minimum of three consecutive bit
times.
2. When a link is invalid and the Link Monitor Function detects the presence of data, the ICS1893Y-10
does not transition the link to the valid state until after the reception of the present packet is complete.
3. Enabling or disabling the Smart Squelch Function affects the Link Monitor function.
4. A transition from the invalid state to the valid state does not automatically update the latching-low Link
Status bit.
6.5.6 10Base-T Operation: Smart Squelch
The Smart Squelch Function imposes more stringent requirements on the Link Monitor Function regarding
the definition of a valid link, thereby providing a level of insurance that spurious noise is not mistaken for a
valid link during cable installation.
An STA can control the execution of the ICS1893Y-10 Smart Squelch Function using bit 18.0 (the Smart
Squelch Inhibit bit in the 10Base-T Operations Register). When bit 18.0 is logic:
• Zero (the default), an ICS1893Y-10 enables its Smart Squelch Function. In this case, the Link Monitor
must confirm the presence of both data and a valid IDL at the end of the packet before declaring a link
valid.
• One, an ICS1893Y-10 disables or inhibits its Smart Squelch Function. In this case, the Link Monitor does
not have to confirm the presence of an IDL to declare a link valid (that is, the reception of any data is
sufficient).
In 10Base-T mode, an ICS1893Y-10 appends an IDL to the end of each packet during data transmission.
The receiving PHY (that is, the remote link partner) sees this IDL and removes it from the data stream.
6.5.7 10Base-T Operation: Carrier Detection
The ICS1893Y-10 has a 10Base-T Carrier Detection Function that establishes the state of its Carrier Sense
signal (CRS), based upon the state of its Transmit and Receive state machines. These functions indicate
whether the ICS1893Y-10 is (1) transmitting data, (2) receiving data, or (3) in a collision state (that is, the
ICS1893Y-10 is both transmitting and receiving data on its twisted-pair medium, as defined in the ISO/IEC
8802-3 standard). When the ICS1893Y-10 is configured for:
• Half-duplex operations, the ICS1893Y-10 asserts its CRS signal when either transmitting or receiving
data.
• Full-duplex operations (or when it is in Repeater mode), the ICS1893Y-10 asserts its CRS signal only
when it is receiving data.
6.5.8 10Base-T Operation: Collision Detection
The ICS1893Y-10 has a 10Base-T Collision Detection Function that establishes the state of its Collision
Detection signal (COL) based upon both (1) the state of its Receiver state machine and (2) the state of its
Transmit state machine. When the ICS1893Y-10 is operating in:
• Half-duplex mode, the ICS1893Y-10 asserts its COL signal to indicate it is receiving data while
transmission of data is also in progress.
• Full-duplex mode, the ICS1893Y-10 always sets its COL signal to FALSE.
ICS1893Y-10 Rev F 1/20/04
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
55
January, 2004