Fast Ethernet 10/100 Quad Transceivers — LXT974/LXT975
Table 54. Port Configuration Register (Address 19, Hex 13) (Continued)
Bit
Name
Description
Type 1
Default
Scrambler
Bypass
1 = Bypass transmit scrambler and receive descrambler.
0 = Normal operation (scrambler and descrambler enabled).
19.3
R/W
Note 3
(100BASE-T
only)
1 = Enable 100BASE fiber interface.
19.2
19.1
19.0
100BASE-FX
Reserved
R/W
R/W
R/W
Note 4
0 = Enable 100BASE twisted pair interface.
Write as 0; ignore on read.
0
0
1 = Disconnect TP transmitter from line.
0 = Normal operation.
Transmit
Disconnect
1. R/W = Read/Write
2. If auto-negotiation is disabled, the default value of bit 19.8 is determined by pin 115 (CFG_1). If CFG_1 is High, the default
value of
bit 19.8 = 1.
If CFG_1 is Low, the default value of bit 19.8 = 0. If auto-negotiation is enabled, the default value of bit 19.8 = 0.
3. The default value of bit 19.3 is determined by BYPSCR. If BYPSCR is High, the default value of bit 19.3 = 1.
If BYPSCR is Low, the default value of bit 19.3 = 0.
4. The default value of bit 19.2 is determined by the SD/TPn pin for the respective port.
If SD/TPn is tied Low, the default value of bit 19.2 = 0. If SD/TPn is not tied Low, the default value of bit 19.2 = 1.
On the LXT975, this bit is ignored on ports 0 and 2 that operate in twisted-pair mode only.
Table 55. Port Status Register (Address 20, Hex 14)
Bit
Name
Description
Type 1
Default
20.15:14 Reserved
Write as 0, ignore on read.
R/W
N/A
1 = Link is up.
0 = Link is down.
Link bit 20.13 is a duplicate of bit 1.2, except that it is a dynamic
indication, whereas bit 1.2 latches Low.
20.13
20.12
Link
RO
RO
0
Duplex
Mode
1 = Full-Duplex.
0 = Half-Duplex.
Note 2
1 = 100 Mbps operation.
0 = 10 Mbps operation.
20.11
20.10
Speed
RO
Note 2
N/A
Reserved
Ignore.
RO/LH
1 = Auto-negotiation process complete.
0 = Auto-negotiation process not complete.
Auto-Negotiation Complete bit 20.9 is a duplicate of bit 1.5.
Auto-Negotiation
Complete
20.9
RO/LH
0
1 = Three identical and consecutive link code words received.
0 = Three identical and consecutive link code words not received.
Page Received bit 20.8 is a duplicate of bit 6.1.
Page
Received
20.8
20:7
20.6
RO/LH
R/W
0
0
0
Reserved
Write as 0, ignore on read.
Stream cipher
lock (100BASE-
TX only)
1 = Stream cipher locked.
0 = Stream cipher not locked.
RO
1 = Symbol error detected.
RO/
LH
20.5
Symbol Error
N/A
0 = No symbol error detected.
1. R/W = Read /Write
RO = Read Only
LH = Latching High
2. Bits 20.12 and 20.11 reflect the current operating mode of the LXT974/975.
Datasheet
71
INTEL [ INTEL ]
