88e3015 Marvell Semiconductor, Inc., 88e3015 Datasheet - Page 40

• Manufacturer Part Number: 88e3015
• Description: Integrated 10/100 Fast Ethernet Transceiver
• Manufacturer: Marvell Semiconductor, Inc.

Table 21:
2.10 Auto MDI/MDIX Crossover
The 88E3015/88E3018 devices automatically determine whether or not it needs to cross over between pairs so
that an external crossover cable is not required. If the 88E3015/88E3018 devices interoperate with a device that
cannot automatically correct for crossover, the 88E3015/88E3018 devices make the necessary adjustment prior to
commencing Auto-Negotiation. If the 88E3015/88E3018 devices interoperate with a device that implements MDI/
MDIX crossover, a random algorithm as described in IEEE 802.3 section 40.4.4 determines which device per-
forms the crossover.
When the 88E3015/88E3018 devices interoperate with legacy 10BASE-T devices that do not implement Auto-
Negotiation, the 88E3015/88E3018 devices follow the same algorithm as described above since link pulses are
present. However, when interoperating with legacy 100BASE-TX devices that do not implement Auto-Negotiation
(i.e. link pulses are not present), the 88E3015/88E3018 devices use signal detect to determine whether or not to
crossover.
The Auto MDI/MDIX crossover function can be disabled via Register 16.5:4.
The 88E3015/88E3018 devices are set to MDI mode by default if auto MDI/MDIX crossover is disabled at hard-
ware reset.
Auto MDI/MDIX should be disabled for 100BASE-FX mode. MDI should be forced for 100BASE-FX.
The pin mapping in MDI and MDIX modes is specified in
details.
Doc. No. MV-S103657-00, Rev. C
Page 40
Ph ysica l Pin
MDIP/N[1]
MDIP/N[0]
MDI/MDIX Pin Functions
88E3015/88E3018
Integrated 10/100 Fast Ethernet Transceiver
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Document Classification: Proprietary Information
MDIX
CONFIDENTIAL
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Table
21. Refer to
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Figure 33 on page 117
M DI
October 26, 2006, Advance
Copyright © 2006 Marvell
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