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Software Developer’s Manual 241
Register Descriptions
13.4.7.1.1 PHY Control Register
PCTRL (00d; R/W)
Table 13-16. PHY Control Register Bit Description
Field Bit(s) Description Mode HW Rst SW Rst
Reserved 5:0
These bits are reserved and should be
set to 000000b.
RO
RW
1
Always
000000b
Speed Selection
(MSB)
6
Speed Selection is determined by bits 6
(MSB) and 13 (LSB) as follows.
11b = Reserved
10b = 1000 Mbps
01b = 100 Mbps
00b = 10 Mbps
A write to these bits do not take effect
until a software reset is asserted,
Restart Auto-Negotiation is asserted, or
Power Down transitions from power
down to normal operation.
82544GC/EI only:
The Speed Selection bits take on the
values set by external pins ANEG[3:0]
on hardware reset only.
Bit 6: ANEG[3] | ANEG[2] | (MODE[3:0]
is one of xx01b, 1x00b, 001xb, 0111b).
Bit 13: (ANEG[3:1] = 001b) and
(MODE[3:0] is not any of xx01b, 1x00b,
001xb, 0111b).
R/W 1b
ANEG[3:2]
MODE[3:0]
Update
Collision Test 7
1b = Enable COL signal test.
0b = Disable COL signal test.
R/W 0b 0b
Duplex Mode 8
1b = Full Duplex.
0b = Half Duplex.
82544GC/EI only:
The Duplex bit takes on the value set by
external pins ANEG[3:2, 0] on hardware
reset only.
Bit 8: ANEG[3:2,0] = 001 | ANEG[3].
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 power.
R/W
1b
ANEG[3:2,
0]
Update
Restart Auto-
Negotiation
9
1b = Restart Auto-Negotiation Process.
0b = Normal operation.
Auto-Negotiation automatically restarts
after hardware or software reset
regardless of whether or not the restart
bit is set.
R/W,
SC
0b
Self
Clear
Isolate 10
1b = Isolate.
0b = Normal operation.
R/W 0b 0b