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Software Developer’s Manual 227
Register Descriptions
FRCDPLX 12 0b
Force Duplex
When set, software can override the duplex indication from the
PHY which is in internal PHY mode. When set the CTRL.FD bit
sets duplex. When cleared, the CTRL.FD is ignored.
Reserved 17:13 0b
Reserved
Should be written with 0b to ensure future compatibility.
Read as 0b
SDP0_DATA 18 0b
2
SDP0 Data Value. Used to read (write) value of software-
controllable IO pin SDP0. If SDP0 is configured as an output
(SDP0_IODIR=1b), this bit controls the value driven on the pin
(initial value EEPROM-configurable). If SDP0 is configured as
an input, reads return the current value of the pin.
SDP1_DATA 19 0b
2
SDP1 Data Value. Used to read (write) value of software-
controllable IO pin SDP1. If SDP1 is configured as an output
(SDP1_IODIR=1b), this bit controls the value driven on the pin
(initial value EEPROM-configurable). If SDP1 is configured as
an input, reads return the current value of the pin.
ADVD3WUC 20 0b
2
D3Cold Wakeup Capability Advertisement Enable. When set,
D3Cold wakeup capability is advertised based on whether the
AUX_PWR pin advertises presence of auxiliary power (yes if
AUX_PWR is indicated, no otherwise). When 0b, however,
D3Cold wakeup capability is not advertised even if AUX_PWR
presence is indicated. Formerly used as SDP2 pin data value,
initial value is EEPROM-configurable.
Note: Not applicable to the 82541ER.
EN_PHY_
PWR_MGMT
21
0b
2
1b
1
PHY Power-Management Enable. When set, the PHY is
informed of power-state transitions and attempts to auto-
negotiate advertising lower line speeds only (10 or 100 Mb/sec)
when entering D3 or D0u power states with wakeup or
manageability enabled. It again re-negotiates, advertising full
speed capabilities (10/100/1000 Mbps) when transitioning back
to full D0 operational state. If this bit is clear, the PHY automatic
speed/power management capability is disabled, and the PHY
remains operational at its current line speed through power-
state transitions. Formerly used as SDP3 pin data value, initial
value is EEPROM-configurable.
SDP0_IODIR 22 0b
2
SDP0 Pin Directionality. Controls whether software-controllable
pin SDP0 is configured as an input or output (0b = input, 1b =
output). Initial value is EEPROM-configurable. This bit is not
affected by software or system reset, only by initial power-on or
direct software writes.
SDP1_IODIR 23 0b
2
SDP1 Pin Directionality. Controls whether software-controllable
pin SDP1 is configured as an input or output (0b = input, 1b =
output). Initial value is EEPROM-configurable. This bit is not
affected by software or system reset, only by initial power-on or
direct software writes.
Reserved 25:24 0b
Reserved. Formerly used as SDP2and SDP3 pin input/output
direction control.
Field Bit(s)
Initial
Value
Description