ICS1894-40 Datasheet, PDF (6/52 Pages) Integrated Device Technology – 10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE

ICS1894-40
10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE
PHYCEIVER
• Physical Medium Attachment sublayer (PMA)
• Physical Medium Dependent sublayer (PMD)
• Auto-Negotiation sublayer
The ICS1894-32 is transparent to the next layer of the OSI
model, the link layer. The link layer has two sublayers: the
Logical Link Control sublayer and the MAC sublayer. The
ICS1894-32 can interface directly to the MAC.
The ICS1894-32 transmits framed packets acquired from its
MAC Interface and receives encapsulated packets from
another PHY, which it translates and presents to its MAC
Interface.
Note:
As per the ISO/IEC standard, the
ICS1894-32 does not affect, nor is it
affected by, the underlying structure of the
MAC frame it is conveying.
100Base-TX Operation
During 100Base-TX data transmission, the ICS1894-32
accepts packets from a MAC and inserts Start-of-Stream
Delimiters (SSDs) and End-of-Stream Delimiters (ESDs)
into the data stream. The ICS1894-32 encapsulates each
MAC frame, including the preamble, with an SSD and an
ESD. As per the ISO/IEC Standard, the ICS1894-32
replaces the first octet of each MAC preamble with an SSD
and appends an ESD to the end of each MAC frame.
When receiving data from the medium, the ICS1894-32
removes each SSD and replaces it with the pre-defined
preamble pattern before presenting the nibbles to its MAC
Interface. When the ICS1894-32 encounters an ESD in the
received data stream, signifying the end of the frame, it ends
the presentation of nibbles to its MAC Interface. Therefore,
the local MAC receives an unaltered copy of the transmitted
frame sent by the remote MAC.
During periods when MAC frames are being neither
transmitted nor received, the ICS1894-32 signals and
detects the IDLE condition on the Link Segment. In the
100Base-TX mode, the ICS1894-32 transmit channel sends
a continuous stream of scrambled ones to signify the IDLE
condition. Similarly, the ICS1894-32 receive channel
continually monitors its data stream and looks for a pattern
of scrambled ones. The results of this signaling and
monitoring provide the ICS1894-32 with the means to
establish the integrity of the Link Segment between itself
and its remote link partner and inform its Station
Management Entity (STA) of the link status.
For 100M data transmission, the ICS1894-32 MAC
Interface is configured to provide a 100M Media
Independent Interface (MII).
10Base-T Operation
During 10Base-T data transmission, the ICS1894-32 inserts
only the IDL delimiter into the data stream. The ICS1894-32
appends the IDL delimiter to the end of each MAC frame.
However, since the 10Base-T preamble already has a
Start-of-Frame delimiter (SFD), it is not required that the
ICS1894-32 insert an SSD-like delimiter.
When receiving data from the medium (such as a
twisted-pair cable), the ICS1894-32 uses the preamble to
synchronize its receive clock. When the ICS1894-32
receive clock establishes lock, it presents the preamble
nibbles to its MAC Interface. The 10M MAC Interface uses
the standard MII Interface.
In 10M operations, during periods when MAC frames are
being neither transmitted nor received, the ICS1894-32
signals and detects Normal Link Pulses. This action allows
the integrity of the Link Segment with the remote link partner
to be established and then reported to the ICS1894-32’s
STA.
SQE and Jabber Function (10Base-T only)
In 10Base-T operation, a short pulse is put out on the COL
pin after each frame is transmitted. This SQE Test is
required as a test of the 10Base-T transmit/receive path. If
transmit enable (TXEN) is high for more than 20 ms
(jabbering), the 10Base-T transmitter is disabled and COL is
asserted high. If TXEN is then driven low for more than 250
ms, the 10Base-T transmitter is re-enabled and COL is
de-asserted (returns to low).
Auto-Negotiation
The ICS1894-40 conforms to the auto-negotiation protocol,
defined in Clause 28 of the IEEE 802.3u specification.
Autonegotiation is enabled by either hardware pin strapping
(pin 20) or software (register 0h bit 12).
Auto-negotiation allows unshielded twisted pair (UTP) link
partners to select the highest common mode of operation.
Link partners advertise their capabilities to each other, and
then compare their own capabilities with those they received
from their link partners. The highest speed and duplex
IDT™ / ICS™ 10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE 6
ICS1894-40 REV C 092909