Flexible Quad Ethernet Repeater
—
LXT914
Datasheet
21
2.5
10BASE-T Port Operation
2.5.1
10BASE-T Reception
Each LXT914 10BASE-T port receiver acquires data packets from its twisted-pair input (TPDIP/
TPDIN). An internal RC filter and an intelligent squelch function discriminate noise from link test
pulses and valid data streams. The receive function is activated only by valid data streams (above
the squelch level and with proper timing). If the differential signal at the DI circuit inputs falls
below 75% of the threshold level (unsquelched) for eight bit times (typical), the port receiver enters
the idle state.
Table 11. Packet Status Register Bit Assignments
Register
D7
D6
D5
D4
D3
D2
D1
D0
PSR(0)
COL2
COL1
COLA
RX4
RX3
RX2
RX1
RXA
PSR(1)
PR2
PR1
LLS4
LLS3
LLS2
LLS1
COL4
COL3
PSR(2)
SPA
AP4
AP3
AP2
AP1
APA
PR4
PR3
PSR(3)
LP3
LP2
LP1
LPA
SP4
SP3
SP2
SP1
PSR(4)
RXJABA
MJLP
LCOL4
LCOL3
LCOL2
LCOL1
LCOLA
LP4
PSR(5)
RES
RXCOL
MANCV
FIFOER
RXJAB4
RXJAB3
RXJAB2
RXJAB1
Table 12. Packet Status Register Bit Definitions
Bit
Definition
RX
x
Received Packet on Twisted-Pair Port 1-4 or on AUI Port
COL
x
Transmit Collision of Twisted -Pair Port 1-4 or on AUI Port
LLSC
x
Link Loss State on Twisted-Pair Port 1-4 or on AUI Port
PR
x
Polarity reversed on Twisted-Pair Port 1-4 or on AUI Port
AP
x
Auto-Partition circuit isolated Twisted-Pair Port 1-4 or the AUI Port
SP
x
Short Packet (less than 74 bits) on Twisted-Pair Port 1-4 or on AUI Port
LP
x
Long Packet (more than 1.3 ms) on Twisted-Pair Port 1-4 or on AUI Port
LCOL
x
Late Collision on Twisted-Pair Port 1-4 or on AUI Port
MJLP
MAU Jabber Lockup Protection
RXJAB
x
Receive Jabber Lockup Protection
FIFOER
FIFO overflow/underflow
MANCV
Manchester Code Violation
RXCOL
Receive Collision on the AUI Port
RES
Reserved. Not used
The notation ABCD
x
means bit ABCD associated with port
x
, which can be any of the four Twisted-Pair
Ports or the AUI Port.