82801DB Datasheet, PDF (268/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

LAN Controller Registers (B1:D8:F0)
7.2.6
Management Data Interface (MDI) Control Register
Offset Address: 10–13h
Default Value: 0000 0000h
Attribute:
Size:
R/W (special)
32 bits
The Management Data Interface (MDI) Control register is a 32-bit field and is used to read and
write bits from the LAN Connect component. This register may be written as a 32-bit entity, two
16-bit entities, or four 8-bit entities. The LAN controller will only accept the command after the
high byte (offset 13h) is written, therefore the high byte must be written last.
Bit
Description
31:30
29
28
27:26
25:21
20:16
15:0
These bits are reserved and should be set to 00b.
Interrupt Enable — R/W.
0 = Disable.
1 = Enables the LAN controller to assert an interrupt to indicate the end of an MDI cycle.
Ready — R/W.
0 = Expected to be reset by software at the same time the command is written.
1 = Set by the LAN controller at the end of an MDI transaction.
Opcode — R/W. These bits define the opcode:
00 = Reserved
01 = MDI write
10 = MDI read
11 = Reserved
LAN Connect Address — R/W. This field of bits contains the LAN Connect address.
LAN Connect Register Address — R/W. This field of bits contains the LAN Connect Register
Address.
Data — R/W. In a write command, software places the data bits in this field, and the LAN controller
transfers the data to the external LAN Connect component. During a read command, the LAN
controller reads these bits serially from the LAN Connect, and software reads the data from this
location.
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Intel^® 82801DB ICH4 Datasheet