Datasheet

78Q2120C

10/100BASE-TX

Transceiver

MR4: Auto-Negotiation Advertisement Register

BIT SYMBOL TYPE DEFAULT DESCRIPTION

4.15 NP R 0

Next Page: Not supported. Reads logic zero.

4.14 RSVD R 0

Reserved

4.13 RF R/W 0

Remote Fault: Setting this bit to ‘1’ allows the device to indicate to

the link partner a Remote Fault Condition.

4.12:5 TAF R/W (0Fh)

Technology Ability Field: The default value of this field is dependent

upon the MR1.15:11 register bits. This field can be overwritten by

management to auto-negotiate to an alternate common technology.

Writing to this register has no effect until auto-negotiation is re-

initiated.

4.12 A7 R 0

Reserved for future technology.

4.11 A6 R/W 0

Reserved

4.10 A5 R/W 0

Reserved.

4.9 A4 R 0

100BASE-T4: The 78Q2120C does not support 100BASE-T4

operation.

4.8 A3 R/W (1)

100BASE-TX Full Duplex: If the MR1.14 bit is ‘1’, this bit will be set

to ‘1’ upon reset and will be writeable. Otherwise, this bit cannot be

set to ‘1’ by the management.

4.7 A2 R/W (1)

100BASE-TX: If the MR1.13 bit is ‘1’, this bit will be set to ‘1’ upon

reset and will be writeable. Otherwise, this bit cannot be set to ‘1’ by

the management.

4.6 A1 R/W (1)

10BASE-T Full Duplex: If the MR1.12 bit is ‘1’, this bit will be set to

‘1’ upon reset and will be writeable. Otherwise, this bit cannot be set

to ‘1’ by the management.

4.5 A0 R/W (1)

10BASE-T: If the MR1.11 bit is ‘1’, this bit will be set to ‘1’ upon reset

and will be writeable. Otherwise, this bit cannot be set to ‘1’ by the

management.

4.4:0 S4:0 R 01h

Selector Field: Hard coded with the value of ‘00001’ for IEEE 802.3.