ICS1893 Datasheet, PDF (42/152 Pages) Integrated Circuit Systems – 3.3-V 10Base-T/100Base-TX Integrated PHYceiver™

ICS1893 Data Sheet - Release
Chapter 7 Functional Blocks
7.2.4 Auto-Negotiation: Reset and Restart
If enabled, execution of the ICS1893 auto-negotiation process occurs at power-up and upon management
request. There are two primary ways to begin the Auto-Negotiation state machine:
• ICS1893 reset
• Auto-Negotiation Restart
7.2.4.1 Auto-Negotiation Reset
During a reset, the ICS1893 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 ICS1893 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 ICS1893 reset can alter these
status bits.
Any of the following situations initiates a restart of the ICS1893 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.
• In hardware mode:
– Toggling the ANSEL (Auto-Negotiation Select) pin 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 ICS1893’s
remote link partner. However, some situations can prevent the auto-negotiation process from properly
achieving this goal. For these situations, the ICS1893 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
ICS1893 Rev C 6/6/00
Copyright © 2000, Integrated Circuit Systems, Inc.
All rights reserved.
42
June, 2000