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MII PHY Registers
2-15
ThunderLAN Registers
2.5 MII PHY Registers
Figure 2–6. MII PHY Registers
Register
Vendor-specific registers
Reserved by IEEE 802.3
Autonegotiation next page transmit
Autonegotiation expansion
Autonegotiation link-partner ability
Autonegotiation advertisement
PHY generic identifier (low)
PHY generic identifier (high)
PHY generic status register
PHY generic control register
0x1F
through
0x10
0x0F
through
0x08
0x07
0x06
0x05
0x04
0x03
0x02
0x01
0x00
Vendor-specific registers
Reserved
Reserved
Reserved
AN next page transmit
AN expansion
AN link-partner ability
AN advertisement
PHY identifier
PHY identifier
Status
Control
Vendor-specific registers
Vendor-specific registers
Description
The 802.3 standard specifies a basic set of registers that must be present.
These include a control register at 0x00 and a status register at 0x01. An ex-
tended set from 0x02 through 0x1F can also be implemented. Within the ex-
tended set, 0x02 through 0x07 are defined and 0x08 through 0x0F are re-
served. The area between 0x10 and 0x1F can be used for vendor-specific ap-
plications. The basic set of registers is shown in dark gray above. The ex-
tended registers are shown in lighter gray and white. The light gray registers
are those defined by 802.3, and the white registers are vendor-specific. The
register specification for the internal 10Base-T PHY in ThunderLAN control-
lers is shown in Appendix A. We have also included the register specification
for the TNETE211 100VG-AnyLAN physical media interface (PMI) in Appen-
dix B.
The PHY registers are accessed to:
Initialize the PHY, bring it in and out of reset, and isolate it from the MII
Set PHY options, such as duplex and loopback
Determine the type of speed and protocol supported by the PHY
Conduct autonegotiation, if supported
Select any vendor-specific options
The control register (GEN_ctl in ThunderLAN products) controls PHY options
such as reset, loopback, duplex, and autonegotiation enable. It also powers
down and isolates the PHY from the MII.