ICS1893 Datasheet, PDF (40/152 Pages) Integrated Circuit Systems – 3.3-V 10Base-T/100Base-TX Integrated PHYceiver™

ICS1893 Data Sheet - Release
Chapter 7 Functional Blocks
7.2.1 Auto-Negotiation General Process
The Auto-Negotiation sublayer uses a physical signaling technique that is transparent at the packet level
and all higher protocol levels. This technique builds on the link pulse mechanism employed in 10Base-T
operations and is fully compliant with clause 28 of the ISO/IEC 8802-3 standard.
During the auto-negotiation process, both the ICS1893 and its remote link partner use Fast Link Pulses
(FLPs) to simultaneously ‘advertise’(that is, exchange) information on their respective technology
capabilities as follows:
1. For the auto-negotiation process to take place, both the ICS1893 and its remote link partner must first
both support and be enabled for Auto-Negotiation.
2. The ICS1893 obtains the data for its FLP bursts from the Auto-Negotiation Advertisement Register
(Register 4).
3. Both the ICS1893 and the remote link partner substitute Fast Link Pulse (FLP) bursts in place of the
Normal Link Pulses (NLPs). In each FLP burst, the ICS1893 transmits information on its technology
capability through its Link Control Word, which includes link configuration and status data.
4. Similarly, the ICS1893 places the Auto-Negotiation data received from its remote link partner's FLP
bursts into the Auto-Negotiation Link Partner Ability Register (Register 5).
5. After the ICS1893 and its remote link partner exchange technology capability information, the ICS1893
Auto-Negotiation sublayer contrasts the data in Registers 4 and 5 and automatically selects for the
operating mode the highest-priority technology that both Register 4 and 5 have in common. (That is,
both the ICS1893 and its remote link partner use a predetermined priority list for selecting the operating
mode, thereby ensuring that both sides of the link make the same selection.) As follows from Annex
28B of the ISO/IEC 8802-3 standard, the pre-determined technology priorities are listed from 1 (highest
priority) to 5 (lowest priority):
(1) 100Base-TX full duplex
(2) 100Base-T4. (The ICS1893 does not support this technology.)
(3) 100Base-TX (half duplex)
(4) 10Base-T full duplex
(5) 10Base-T (half duplex)
Table 7-1 shows an example of how the selection process of the highest-priority technology takes
place.
Table 7-1. Example of Selection Process of Highest-Priority Technology
If Register 4 Has These
Technologies:
(3) 100Base-TX half duplex
(4) 100Base-T full duplex
If Register 5 Has These
Technologies:
Resulting Highest-Priority Common
Technology from Auto-Negotiation
Sublayer
(1) 100Base-TX full duplex (3) 100Base-TX half duplex
(3) 100Base-TX half duplex
6. To indicate that the auto-negotiation process is complete, the ICS1893 sets bits 1.5 and 17.4 high to
logic one. After successful completion of the auto-negotiation process, the ICS1893 Auto-Negotiation
sublayer performs the following steps:
a. It sets to logic one the Status Register’s Auto-Negotiation Complete bit (bit 1.5, which is also
available in the QuickPoll register as bit 17.4).
b. It enables the negotiated link technology (such as the 100Base Transmit modules and 100Base
Receive modules).
c. It disables the unused technologies to reduce the overall power consumption.
ICS1893 Rev C 6/6/00
Copyright © 2000, Integrated Circuit Systems, Inc.
All rights reserved.
40
June, 2000