ICS1893 datasheet(43/152 Pages) ICST

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Chapter 7

Functional Blocks

ICS1893 Rev C 6/6/00

June, 2000

ICS1893 - Release

Auto-Negotiation Link Partner Ability Register and determine the highest-performance operating mode in

common with the capabilities it is advertising.

The ISO/IEC-defined priority table determines the established link type. As a simpler alternative, the STA

can read the QuickPoll Detailed Status Register and determine the link type from the Data Rate bit (bit

17.15) and the Duplex bit (bit 17.14). For convenience, the QuickPoll Register also includes the Link Status

bit (bit 17.0) and the Auto-Negotiation Complete bit (bit 17.4).

If (1) the auto-negotiation process does not complete, or (2) the link is not established, or (3) both the

auto-negotiation process does not complete and the link is not established, then the STA can determine the

cause of the link failure by using the outputs of the ICS1893 Auto-Negotiation Progress Monitor.

The Auto-Negotiation Progress Monitor provides the STA with four status bits of data to indicate both the

history and the present state of the auto-negotiation process. This status data is provided in the QuickPoll

Detailed Status register by using the Auto-Negotiation Complete bit (bit 17.4) as well as bits 17.13:11. The

bit order, from most-significant bit to least-significant bit, is 17.4, 17.13, 17.12, and 17.11. Using these four

bits, the Auto-Negotiation Progress Monitor provides nine state codes detailing the operation of the

auto-negotiation process for the STA. [For more information, see Section 8.12.3, “Auto-Negotiation

Progress Monitor (bits 17.13:11)”.]

The nine Auto-Negotiation Progress Monitor state codes are 0h through 8h and Fh. The Auto-Negotiation

Progress Monitor automatically latches the values of the Auto-Negotiation Arbitration State Machine into

the status bits only if the value of the present state is greater than the value that is currently in the status

bits.

For example, if the status bits have a value of 3h and the auto-negotiation process moves into:

• State 1, the Auto-Negotiation Progress Monitor does not update the status bits to indicate the new state.

• State 5, the Auto-Negotiation Progress Monitor updates the status bits to indicate the new state, State 5.

In this case, the status bits increase in value until either the auto-negotiation process successfully

completes or the STA reads the Auto-Negotiation Progress Monitor status bits.

When the STA reads the status bits, the present state of the auto-negotiation process is automatically

latched into the status bits, regardless of how they compare to the value currently in the latch. However,

the read presents the STA with the previously latched values of the status bits, not the values just

latched into the status register by the read. Therefore, the STA must perform two reads of the status bits

to determine the present state of the Auto-Negotiation Arbitration State Machine.

The first read provides a 'history' of the auto-negotiation process, (that is, the highest state achieved by

the auto-negotiation process). The second read provides the present state of the auto-negotiation

process. This behavior allows management to determine the greatest forward progress made by the

auto-negotiation logic, which is valuable for diagnosing link errors and failures.

Note:

Once the auto-negotiation process completes successfully, the value of all the Progress Monitor

status bits and the Auto-Negotiation Complete bit have a value of logic one. A read operation of the

QuickPoll Register provides a value of logic one for the Auto-Negotiation Complete bit and an octal

value of 111 for the status bits.

Subsequent reads of the QuickPoll Register also provide a value of logic one for the

Auto-Negotiation Complete bit. However, the value of the status bits are 000b, providing the link

remains established.

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