AV1890Y Просмотр технического описания (PDF) - Integrated Circuit Systems
Номер в каталоге
Компоненты Описание
Список матч
AV1890Y Datasheet PDF : 24 Pages
| |||
ICS1890
Status
Idle
Parallel Detected
Parallel Detection Failure
Ability Matched
Acknowledge Match Failure
Acknowledge Matched
Consistency Match Failure
Consistency Matched
Auto-Negotiation Completed Successfully
A-N Complete
0
0
0
0
0
0
0
0
1
Progress Monitor Status Bits
Bit 2
Bit 1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
1
1
Bit 0
0
1
0
1
0
1
0
1
1
In the event that the link partner does not support auto-
negotiation, backward compatibility is guaranteed because
legacy systems will not respond to the burst (called Fast Link
Pulses). 10Base-T systems will continue to send 10Base-T
link test pulses which will be interpreted by the ICS1890 as
a 10Base-T technology only device. 100Base-TX systems
would send scrambled idle symbols, which would be interpreted
by theICS1890as a 100Base-TX only device. Auto-negotiation
is invoked at power-up, upon request by management, or
manually.
Auto-Negotiation Progress Monitor
Under normal circumstances, Auto-Negotiation is able to
effortlessly establish a connection with the link partner. There
are, however, some situations that may prevent Auto-
Negotiation from completing properly. TheAuto-Negotiation
Progress Monitor is designed to provide detailed information
to a station management entity to assist it in making a connection
in the event that Auto-Negotiation is unable to establish a
connection by itself.
During normal Auto-Negotiation operation, the device ex-
changes capability information with its link partner and then
sets the Auto-Negotiation Complete bit in the Status register
(1:5) (also available in the QuickPoll register as bit 17:4) to a
logic one to indicate that the information exchange has completed
successfully and that Auto-Negotiation has handed off the
link startup process to the negotiated technology.
The entire process, in either case, usually takes less than half
a second to complete. Typically, management will poll the
Auto-Negotiation Complete bit and then the Link Status bit to
determine when a connection has been successfully made
and then the actual type of connection can be determined by
management. This information is all contained in the QuickPoll
register.
When Auto-Negotiation fails, Auto-Negotiation Complete may
never become true or Link Status may never become good.
Station management can detect this condition and discover
why there is a failure to connect by using the detailed information
provided by the Auto-Negotiation Progress Monitor.
The Auto-Negotiation Progress Monitor provides four bits of
status in the QuickPoll Detailed Status register when combined
with the already present Auto-Negotiation Complete bit.
As progress is made through the Auto-Negotiation Arbitration
state machine, higher status values are locked in to the progress
monitor. The status value only is allowed to increase until
either Auto-Negotiation is completed successfully or the
progress monitor status is read by management.
After the status is read by management, the status is reset to
the current status of the Arbitration state machine. After
negotiation has completed successfully, any link failure will
cause the process to being anew.
Auto-Negotiation can also accommodate legacy 10Base-T
and 100Base-TX link partners that do not have Auto-Negotiation
capability. In this case, Auto-Negotiation identifies the link
partner as not being Auto-Negotiation able by setting the
LP_AutoNeg_Able bit (6:0) to a logic zero, identifies the
legacy connection to be made by setting the single bit
corresponding to that technology in the AN Link Partner
Abilities Register (either bit 5:7 or 5:5), and finally indicates
Auto-Negotiation Complete.
This behavior allows management to always determine the
greatest forward progress made by the Auto-Negotiation logic.
9
Share Link: 