MII Management Register Descriptions
1406
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Ethernet Media Access Controller (EMAC)
19.7.5 Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4)
Register, address 0x04
The Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4) register provides the
advertised abilities of the Ethernet PHY used during auto-negotiation. Bits 8:5 represent the Technology
Ability Field bits. This field can be overwritten by software to auto-negotiate to an alternate common
technology. Writing to this register has no effect until auto-negotiation is re-initiated by setting the RANEG
bit in the MR0 register.
Figure 19-25. Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4)
Register
15
14
13
12
9
8
NP
Reserved
RF
Reserved
A3
R-0
R-0
R/W-0
R-0
R/W-1
7
6
5
4
0
A2
A1
A0
S
R/W-1
R/W-1
R/W-1
R-1
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 19-24. Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4)
Register Field Descriptions
Bit
Field
Value
Description
15
NP
Next Page
0
The Ethernet PHY is not capable of Next Page exchanges.
1
The Ethernet PHY is capable of Next Page exchanges to provide more detailed information on the
PHY layer’s capabilities.
14
Reserved
Reserved
13
RF
Remote Fault
0
No Remote Fault condition has been encountered.
1
Indicates to the link partner that a Remote Fault condition has been encountered.
12-9
Reserved
Reserved
8
A3
Technology Ability Field [3]
0
The Ethernet PHY does not support the 100Base-TX full-duplex signaling protocol.
1
The Ethernet PHYr supports the 100Base-TX full-duplex signaling protocol. If software wants to
ensure that this mode is not used, this bit can be cleared and auto-negotiation re-initiated with the
RANEG bit in the MR0 register.
7
A2
Technology Ability Field [2]
0
The Ethernet PHY does not support the 100Base-TX half-duplex signaling protocol.
1
The Ethernet PHY supports the 100Base-TX half-duplex signaling protocol. If software wants to
ensure that this mode is not used, this bit can be cleared and auto-negotiation re-initiated with the
RANEG bit in the MR0 register.
6
A1
Technology Ability Field [1]
0
The Ethernet PHY does not support the 10BASE-T full-duplex signaling protocol.
1
The Ethernet PHY supports the 10BASE-T full-duplex signaling protocol. If software wants to
ensure that this mode is not used, this bit can be cleared and auto-negotiation re-initiated with the
RANEG bit in the MR0 register.
5
A0
Technology Ability Field [0]
0
The Ethernet PHY does not support the 10BASE-T half-duplex signaling protocol.
1
The Ethernet PHY supports the 10BASE-T half-duplex signaling protocol. If software wants to
ensure that this mode is not used, this bit can be cleared and auto-negotiation re-initiated with the
RANEG bit in the MR0 register.
4-0
S
Selector Field
1h
This field encodes 32 possible messages for communicating between Ethernet PHYs.