ICS1892
TSD
Chapter 7 Functional Blocks
10Base-T/100BIaCseS-TX1I8nt9eg2rated PHYceiver™
7.2.2 Auto-Negotiation: Parallel Detection
The ICS1892 supports parallel detection. It is therefore compatible with networks that do not support the
auto-negotiation process. When enabled, the Auto-Negotiation sublayer can detect legacy 10Base-T link
partners as well as 100Base-TX link partners that do not have an auto-negotiation capability.
The Auto-Negotiation sublayer performs this parallel detection function when it does not get a response to
its FLP bursts. In these situations, the Auto-Negotiation sublayer performs the following steps:
1. It sets the LP_AutoNeg_Able bit (bit 6.0) to logic zero, thereby identifying the remote link partner as not
being capable of executing the auto-negotiation process.
2. It sets the bit in the Auto-Negotiation Link Partner Abilities Register that corresponds to the 'parallel
detected' technology [for example, half-duplex, 10Base-T (bit 5.5) or half-duplex, 100Base-TX (bit
5.7)]. IEEE specification allows only half-duplex operation with auto-negotiation paralled detect
partners.
3. It sets the Status Register’s Auto-Negotiation Complete bit (bit 1.5) to logic one, indicating completion
of the auto-negotiation process.
4. It enables the detected link technology and disables the unused technologies.
A remote link partner that does not support the auto-negotiation process does not respond to the
transmitted FLP bursts. The ICS1892 detects this situation and responds according to the data it receives.
The ICS1892 can receive one of five potential responses to the FLP bursts it is transmitting: FLP bursts,
10Base-T link pulses (that is, Normal Link Pulses), scrambled 100Base IDLEs, nothing, or a combination of
signal types.
A 10Base-T link partner transmits only Normal Link Pulses when idle. When the ICS1892 receives Normal
Link Pulses, it concludes that the remote link partner is a device that can use only 10Base-T technology. A
100Base-TX node without an Auto-Negotiation sublayer transmits 100M scrambled IDLE symbols in
response to the FLP bursts. Upon receipt of the scrambled IDLEs, the ICS1892 concludes that its remote
link partner is a 100Base-TX node that does not support the auto-negotiation process. For both 10Base-T
and 100Base-TX nodes without an Auto-Negotiation sublayer, the ICS1892 clears bit 6.0 to logic zero,
indicating that the link partner cannot perform the auto-negotiation process.
If the remote link partner responds to the FLP bursts with FLP bursts, then the link partner is a 100Base-TX
node that can support the auto-negotiation process. In this case, the ICS1892 sets to logic one the
Auto-Negotiation Expansion Register’s Link Partner Auto-Negotiation Ability bit (bit 6.0).
If the Auto-Negotiation sublayer does not receive any signal when monitoring the receive channel, then the
QuickPoll Detailed Status Register’s Signal Detect bit (bit 17.3) is set to logic one, indicating that no signal
is present.
Another possibility is that the ICS1892 senses that it is receiving multiple technology indications. In this
situation, the ICS1892 cannot determine which technology to enable. It informs the STA of this problem by
setting to logic one the Auto-Negotiation Expansion Register’s Parallel Detection Fault bit (bit 6.4).
7.2.3 Auto-Negotiation: Remote Fault Signaling
If the remote link partner detects a fault, the ICS1892 reports the remotely detected fault to the STA by
setting to logic one the Remote Fault Detected bit(s), 1.4, 5.13, and 17.1. The reception of a remote link
fault during the technology exchange also indicates that the remote link partner can perform remote fault
detection and the Remote Fault bit (bit 19.13) is set to logic one. In general, the reception of a remote fault
means that the remote link partner has a problem with the integrity of its receive channel.
Similarly, if the ICS1892 detects a link fault, it transmits a remote fault-detected condition to its remote link
partner. In this situation, the ICS1892 sets to logic one the Auto-Negotiation Link Partner Ability Register’s
Remote Fault Indication bit (bit 5.13). In addition, the ICS1892 sets to logic one the Extended Control
Register’s bit 19.13, indicating that it sent a remote fault to its remote link partner.
ICS1892, Rev. D, 2/26/01
February 26, 2001
© 2000-2001, Integrated Circuit Systems, Inc.
All rights reserved.
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IDT™ / ICS™ 10Base-T/100Base-TX Integrated PHYceiver™
ICS1892
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