LXT980/980A Dual-Speed, 5-Port Fast Ethernet Repeater
Datasheet
87
5.3.6
MII Status Register
The MII Status register is described in
Table 68
. Refer to
Table 67
for bit assignments. This is a 32-
bit register.
Table 66. Interrupt Status Register Bit Definitions
Bit
Name
Type
1
Description
Default
31:8
Reserved
R/W
Reserved - Write as 0s; ignore on read.
N/A
7
Far End
Fault
R/W
A
‘
1
’
indicates that one of four conditions has occurred:
1. A port in fiber mode received the remote fault code from its link partner.
2. A port in auto-negotiation received 3 FLPs in a row with the remote fault bit set.
3. A port is in fiber mode with remote fault reporting enabled, and either the receive
PLL is unlocked or the signal detect input has been lost.
4. A port in auto-negotiation is transmitting FLPs with the remote fault bit set.
In conditions 1 and 2 the link partner has detected the remote fault condition and is
sending it to the LXT980.
In conditions 3 and 4 the LXT980 has detected the remote fault condition and is
sending it to the link partner.
0
6
Reserved
R/W
Reserved - Write as 0s; ignore on read.
0
5
Jabber
R
A
‘
1
’
indicates that a port is in jabber state.
During 100 Mbps operation, jabber occurs when any receiver remains active for
more than 57,500 bit times. The LXT980 exits this state when all receivers return to
the idle condition.
During 10 Mbps operation, jabber occurs when any port remains actively
transmitting for longer than 40,000 to 75,000 bit times. The LXT980 will assert a
minimum-IFG idle period when a port is jabbering.
0
4
Isolate
R/W
A
‘
1
’
indicates that a port has been isolated (100 Mbps only). The LXT980 isolates
any port that transmit more than two successive false carrier events. A false carrier
event is defined as a packet that does not start with a /J/K symbol pair.
0
3
Partition
R/W
A
‘
1
’
indicates that a port has been partitioned.
In 100 Mbps operation, the LXT980 partitions any port that participates in excess of
60 consecutive collisions. In 10 Mbps operation, the LXT980 partitions any port that
participates in excess of 32 consecutive collisions. Once partitioned, the LXT980
will continue monitoring and transmitting to the port, but will not repeat data
received from the port until it properly un-partitions.
0
2
FCC
R/W
A
‘
1
’
indicates that a port has received too many false carrier events
0
1
SA
Change
R/W
A
‘
1
’
indicates that a port address changed from that stored in the
lastSourceAddress register.
0
0
Speed
Change
R/W
A
‘
1
’
indicates that a port speed change was detected.
0
1. R = Read only; R/W = Read/Write.
Table 67. MII Status Register Bit Assignment
31:2
1
0
Reserved
Select 10 Mbps or 100 Mbps
0 = 10 Mbps
1 = 100 Mbps
Select connecting device type
0 = MAC Mode (connected to a PHY)
(Available at 100 Mbps only)
1 = PHY Mode (connected to a MAC)
(Available at either 10 or 100 Mbps)