SMSC LAN9420 - Manual (Page 145)

Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
Datasheet
SMSC LAN9420/LAN9420i 145 Revision 1.22 (09-25-08)
DATASHEET
4.5.10 Special Control/Status Indications
Index (In Decimal): 27 Size: 16 bits
BITS DESCRIPTION TYPE DEFAULT
15 Override AUTOMDIX_EN Strap
0 = AUTOMDIX_EN configuration strap enables or disables HP Auto MDIX.
1 = Override AUTOMDIX_EN configuration strap. PHY Register 27.14 and
27.13 determine MDIX function.
R/W 0b
14 Auto-MDIX Enable
Only effective when 27.15=1, otherwise ignored.
0 = Disable Auto-MDIX. 27.13 determines normal or reversed connection.
1 = Enable Auto-MDIX. 27.13 must be set to 0. R/W 0b
13 Auto-MDIX State
Only effective when 27.15=1, otherwise ignored.
When 27.14 = 0 (manually set MDIX state):
0 = no crossover (TPO = output, TPI = input)
1 = crossover (TPO = input, TPI = output)
When 27.14 = 1 (automatic MDIX) this bit must be set to 0.
Do not use the combination 27.15=1, 27.14=1, 27.13=1.
R/W 0b
12:11 RESERVED RO -
10 VCOOFF_LP
Forces the Receive PLL 10M to lock on the reference clock at all times: 0
– Receive PLL 10M can lock on reference or line as needed (normal
operation) 1 - Receive PLL 10M is locked on the reference clock. In this
mode 10M data packets cannot be received. R/W,
NASR
0b
9:5 RESERVED RO -
4 XPOL
Polarity state of the 10BASE-T:
0 – Normal polarity
1 – Reversed polarity RO 0b
3:0 RESERVED RO -