ICS1893AGLF View Datasheet(PDF) - Integrated Circuit Systems
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'ICS1893AGLF' PDF : 135 Pages View PDF
ICS1893AG Data Sheet - Preliminary
Chapter 7 Functional Blocks
7.2.4 Auto-Negotiation: Reset and Restart
If enabled, execution of the ICS1893AG auto-negotiation process occurs at power-up and upon
management request. There are two primary ways to begin the Auto-Negotiation state machine:
• ICS1893AG reset
• Auto-Negotiation Restart
7.2.4.1 Auto-Negotiation Reset
During a reset, the ICS1893AG initializes its Auto-Negotiation sublayer modules to their default states.
(That is, the Auto-Negotiation Arbitration State Machine and the Auto-Negotiation Progress Monitor reset to
their idle states.) In addition, the Auto-Negotiation Progress Monitor status bits are all set to logic zero. This
action occurs for any type of reset (hardware reset, software reset, or power-on reset).
7.2.4.2 Auto-Negotiation Restart
As with a reset, during an Auto-Negotiation restart, the ICS1893AG initializes the Auto-Negotiation
Arbitration State Machine and the Auto-Negotiation Progress Monitor modules to their default states.
However, during an Auto-Negotiation Restart, the Auto-Negotiation Progress Monitor status bits maintain
their current state. Only three events can alter the state of the Auto-Negotiation Progress Monitor status
bits after a Restart: (1) an STA read operation, (2) a reset, or (3) the Auto-Negotiation Arbitration State
Machine progressing to a higher state or value.
The Auto-Negotiation Progress Monitor Status bits change only if they are progressing to a state with a
value greater than their current state (that is, a state with a higher logical value than that of their current
state). For a detailed explanation of these bits and their operation, see Section 7.2.5, “Auto-Negotiation:
Progress Monitor”.
After the Auto-Negotiation Arbitration State Machine reaches its final state (which is Auto-Negotiation
Complete), only an STA read of the QuickPoll Detailed Status Register or an ICS1893AG reset can alter
these status bits.
Any of the following situations initiates a restart of the ICS1893AG Auto-Negotiation sublayer:
• A link failure
• In software mode:
– Writing a logic one to the Control Register’s Restart Auto-Negotiation bit (bit 0.9), which is a self-
clearing bit.
– Toggling the Control Register’s Auto-Negotiation Enable bit (bit 0.12) from a logic one to a logic zero,
and back to a logic one.
7.2.5 Auto-Negotiation: Progress Monitor
Under typical circumstances, the Auto-Negotiation sublayer can establish a connection with the
ICS1893AG’s remote link partner. However, some situations can prevent the auto-negotiation process from
properly achieving this goal. For these situations, the ICS1893AG has an Auto-Negotiation Progress
Monitor to provide detailed status information to its Station Management (STA) entity. With this status
information, the STA can diagnose the failure mechanism and – in some situations – establish the link by
correcting the problem.
When enabled, the auto-negotiation process typically requires less than 500 ms to execute, independent of
the link partner's ability to perform the auto-negotiation process. Typically, an STA polls both the
Auto-Negotiation Complete bit (bit 1.5) and the Link Status bit (bit 1.2) to determine when a link is
successfully established, either through auto-negotiation or parallel detection. The STA can then poll the
Auto-Negotiation Link Partner Ability Register and determine the highest-performance operating mode in
common with the capabilities it is advertising.
ICS1893AG, Rev. A 04/14/05
Copyright © 2005, Integrated Circuit Systems, Inc.
All rights reserved.
37
April, 2005
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