Datasheet

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DP83865
3.0 Configuration (Continued)
3.2.2 Master/Slave
In 1000BASE-T the two link partner devices have to be
configured, one as Master and the other as Slave. The
Master device by definition uses a local clock to transmit
data on the wire; the Slave device uses the clock recov-
ered of the incoming data from the link partner for transmit-
ting its data. The Master and Slave assignments can be
manually set by using strapping options or register writes.
When the AN_EN pin is strapped low, strapping MULTI_EN
pin low selects Slave and high selects Master mode. Reg-
ister 9 bits 12:11 allows software to overwrite the strapping
Master/Slave setting (Table 30). Note that if both the link
partner and the local device are manually given the same
Master/Slave assignment, an error will occur as indicated
in 1KSTSR 0x0A bit 15.
Depending on what the link partner is configured to, the
manual Master/Slave mode can be resolved to eight possi-
ble outcomes. Only two National PHYs will be able to link
to each other in manual configuration mode.
(Table 32)
3.3 Auto-Negotiation
All 1000BASE-T PHYs are required to support Auto-Nego-
tiation. (The 10/100 Mbps Ethernet PHYs had an option to
support Auto-Negotiation, as well as parallel detecting
when a link partner did not support Auto-Neg.) The Auto-
Negotiation function in 1000BASE-T has three primary pur-
poses:
— Auto-Negotiation of Speed & Duplex Selection
— Auto-Negotiation of Master/Slave Resolution
— Auto-Negotiation of Pause/Asymetrical Pause Resolu-
tion
.
The DP83865 also supports features such as:
— Next Page
— Parallel Detection for 10/100 Mbps
— Restart Auto-Negotiation through software
3.3.1 Speed/Duplex Selection - Priority Resolution
The Auto-Negotiation function provides a mechanism for
exchanging configuration information between the two
ends of a link segment. This mechanism is implemented by
exchanging Fast Link Pulses (FLP). FLP are burst pulses
that provide the signalling used to communicate the abili-
ties between two devices at each end of a link segment.
For further details regarding Auto-Negotiation, refer to
Clause 28 of the IEEE 802.3u specification. The DP83865
supports six different Ethernet protocols: 10BASE-T Full
Duplex, 10BASE-T Half Duplex, 100BASE-TX Full Duplex,
100BASE-TX Half Duplex, 1000BASE-T Full Duplex, and
1000BASE-T Half Duplex. The process of Auto-Negotiation
ensures that the highest performance protocol is selected
(i.e., priority resolution) based on the advertised abilities of
the Link Partner and the local device. (Table 33)
.
Table 29. Speed/Duplex Selection, AN_EN = 0
DUPLEX SPEED[1] SPEED[0] Manual Mode
0 0 0 10BASE-T HD
0 0 1 100BASE-TX HD
0 1 0 1000BASE-T HD
(Between National
PHYs only)
01 1Reserved
1 0 0 10BASE-T FD
1 0 1 100BASE-TX FD
1 1 0 1000BASE-T FD
(Between National
PHYs only)
11 1Reserved
Table 30. 1000BASE-T Master/Slave Sel., AN_EN = 0
MULTI_EN Manual Mode
0Slave mode
1 Master mode
Table 31. Master/Slave Resolution, AN_EN = 0
DP83865
Advertise
Link Partner
Advertise
DP83865
Outcome
Link Partner
Outcome
Manual
Master
Manual
Master
Unresolved
No Link
Unresolved
No Link
Manual
Master
Manual
Slave
Master Slave
Manual
Master
Multi-node
(Auto-neg)
Master Slave
Manual
Master
Single-node
(Auto-neg)
Master Slave
Manual
Slave
Manual
Master
Slave Master
Manual
Slave
Manual
Slave
Unresolved
No Link
Unresolved
No Link
Manual
Slave
Multi-node
(Auto-neg)
Slave Master
Manual
Slave
Single-node
(Auto-neg)
Slave Master
Table 32. Master/Slave Resolution, AN_EN = 0
DP83865
Advertise
Link Partner
Advertise
DP83865
Outcome
Link Partner
Outcome
Manual
Master
Manual
Master
Unresolved
No Link
Unresolved
No Link
Manual
Master
Manual
Slave
Master Slave
Manual
Master
Multi-node
(Auto-neg)
Master Slave
Manual
Master
Single-node
(Auto-neg)
Master Slave
Manual
Slave
Manual
Master
Slave Master
Manual
Slave
Manual
Slave
Unresolved
No Link
Unresolved
No Link
Manual
Slave
Multi-node
(Auto-neg)
Slave Master
Manual
Slave
Single-node
(Auto-neg)
Slave Master