88e3015 Marvell Semiconductor, Inc., 88e3015 Datasheet - Page 30

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

2.3.3.4
The link monitor is responsible for determining if link is established with a link partner. In 10BASE-T mode, link
monitor function is performed by detecting the presence of valid link pulses (NLPs) on the MDI± pins.
In 100BASE-TX mode, link is established by scrambled idles.
See Section
2.3.3.5
In 100BASE-TX mode, the signal detection function is based on the receive signal energy detected on the MDI±
pins that is continuously qualified by the squelch detect circuit, and the local receiver acquiring lock.
2.3.3.6
The SIGDET pin is used to qualify whether there is receive energy on the line. Register 16.6 determines the polar-
ity of the SIGDET pin. When Register 16.6 is set low, the SIGDET pin polarity is active high, otherwise the polarity
is active low.
2.3.4 Decoder
2.3.4.1
In 100BASE-TX mode, the receive data stream is recovered and converted to NRZ. The NRZ stream is descram-
bled and aligned to the symbol boundaries. The aligned data is then parallelized and 5B/4B decoded. The receiver
does not attempt to decode the data stream unless the scrambler is locked. The descrambler “locks” to the scram-
bler state after detecting a sufficient number of consecutive idle code-groups. Once locked, the descrambler con-
tinuously monitors the data stream to make sure that it has not lost synchronization. The descrambler is always
forced into the unlocked state when a link failure condition is detected, or when insufficient idle symbols are
detected.
2.3.4.2
In 10BASE-T mode, the recovered 10BASE-T signal is decoded from Manchester to NRZ, and then aligned. The
alignment is necessary to insure that the start of frame delimiter (SFD) is aligned to the nibble boundary.
2.3.4.3
In 100BASE-FX mode the receive data stream is received and converted to NRZ. The decoding process is identi-
cal to 100BASE-TX except no descrambling is necessary.
Doc. No. MV-S103657-00, Rev. C
Page 30
Copper Signal Detection
Fiber Signal Detection
100BASE-TX
10BASE-T
100BASE-FX
Link Monitor
2.8
for unidirectional enable.
88E3015/88E3018
Integrated 10/100 Fast Ethernet Transceiver
Document Classification: Proprietary Information
CONFIDENTIAL
October 26, 2006, Advance
Copyright © 2006 Marvell