Intel PCI 사용자 설명서

243

Auto-Negotiation 
Enable

12

1b = Enable Auto-Negotiation Process.
0b = Disable Auto-Negotiation Process.
A write to this bit does not take effect 
until a software reset is asserted, 
Restart Auto-Negotiation is asserted, or 
Power Down transitions from power 
down to normal operation.
When the port is switched from power 
down to normal operation, software 
reset and restart Auto-Negotiation are 
performed even if bits Reset and Restart 
Auto-Negotiation are not set by the 
programmer.
If bit 12 is set to 0b and speed is 
manually forced to 1000 Mbps in bits 13 
and 6, then Auto-Negotiation is still 
enabled and only 1000BASE-T full 
duplex is advertised if bit 8 is set to 1b. 
1000BASE-T half duplex is advertised if 
bit 8 is cleared (0b). Duplex settings in 
other registers are ignored. Auto-
Negotiation is required by IEEE for 
proper operation in 1000BASE-T.
82544GC/EI only:
Auto-Negotiation enable takes on the 
value set by external pins ANEG[3:0] on 
hardware reset only.
Bit 12: ANEG[3:2] = 11b.
If MODE[3:0] equals 001xb or 0111b, 
where x equals either 0b or 1b, then the 
ANE bit determines whether 
1000BASE-X Auto-Negotiation is on or 
off. Otherwise ANE determines whether 
10/100/1000BASE-T Auto-Negotiation 
is on or off.

R/W

R/W

1b

ANEG[3:2] 
ENA_XC

Update

Update

Speed Selection 
(LSB)

13

See Speed Selection (MSB), bit 6.

R/W

0b
ANEG[3:1]

2

MODE[3:0]

Update

Loopback

14

1b = Enable loopback.
0b = Disable loopback.

R/W

0b

0b

Reset

15

1b = PHY reset.
0b = Normal operation.

R/W, 
SC

0b

Self 
Clear

1.

82541xx and 82547GI/EI only.

2.

82544GC/EI only.