cs8904 Cirrus Logic, Inc., cs8904 Datasheet - Page 15

• Manufacturer Part Number: cs8904
• Description: Crystal Lan? Quad Ethernet Transceiver
• Manufacturer: Cirrus Logic, Inc.

DS191PP2
If the remote device supports Auto-Negotiation,
but does not share a compatible set of capabilities
with the CS8904, then the CS8904 will indicate
that the Auto-Negotiation was unsuccessful and
that the link is failed through the Auto-Negotiation
output and the Link Status LED output. Auto-
negotiation may also fail if the CS8904 is unable to
exchange a Link Code Word with the remote
device.
When Auto-Negotiation is disabled, the CS8904
sends Normal Link Pulses to the remote Ethernet
device.
3.3.3.3 Receive Polarity Detection and Correction
The CS8904 checks the polarity of the receive half
of the twisted pair cable and automatically corrects
a reversal.
CS8904
Crystal LAN™ Quad Ethernet Transceiver
CIRRUS LOGIC ADVANCED PRODUCT DATABOOK
To detect a reversed pair, the receiver examines
received link pulses and the End-of-Frame (EOF)
sequence of incoming packets. If it detects at least
one reversed link pulse and at least four frames in a
row with negative polarity after the EOF, the
receive pair is considered reversed. Any data
received before the correction of the reversal is
ignored.
3.3.4 Collision Detection
If half duplex operation is selected, the CS8904
detects a 10BASE-T collision whenever the
receiver and transmitter are active simultaneously.
When a collision is present, the collision detection
circuit informs the digital controller by asserting
the collision signal. If full duplex operation is
selected, the collision detection circuit is disabled.
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