GD82559ER Datasheet, PDF (47/94 Pages) Intel Corporation – PCI Controller

Networking Silicon — GD82559ER
6.1.4
6.1.5
6.1.5.1
6.1.5.2
6.1.6
6.2
6.2.1
100BASE-TX Collision Detection
100BASE-TX collisions in half duplex mode only are detected similarly to 10BASE-T collision
detection, via simultaneous transmission and reception.
100BASE-TX Link Integrity and Auto-Negotiation Solution
The 82559 Auto-Negotiation function automatically configures the device to the technology,
media, and speed to operate with its link partner. Auto-Negotiation is widely described in IEEE
specification 802.3u, clause 28. The PHY unit supports 10BASE-T half duplex, 10BASE-T full
duplex, 100BASE-TX half duplex, and 100BASE-TX full duplex.
The PHY unit has two Physical Media Attachment (PMA) technologies with its link integrity
function, 10BASE-T and 100BASE-TX.
Link Integrity
In 100BASE-TX, the link integrity function is determined by a stable signal status coming from the
TP-PMD block. Signal status is asserted when the PMD detects breaking squelch energy and the
right bit error rate according to the ANSI specification.
Auto-Negotiation
The PHY unit fully supports IEEE 802.3u, clause 28. The technology, 10BASE-T or 100BASE-
TX, is determined by the Auto-Negotiation result.
Speed and duplex auto-select are functions of Auto-Negotiation. However, these parameters may
be manually configured via the MII management interface (MDI registers).
Auto 10/100 Mbps Speed Selection
The MAC may either allow the PHY unit to automatically select its operating speed or force the
PHY into 10 Mbps or 100 Mbps mode. The Management Data Interface (MDI) can control the
PHY unit speed mode.
The PHY unit auto-select function determines the operation speed of the media based on the link
integrity pulses it receives. If no Fast Link Pulses (FLPs) are detected and Normal Link Pulses
(NLPs) are detected, the PHY unit defaults to 10 Mbps operation. If the PHY unit detects a speed
change, it dynamically changes its transmit clock and receive clock frequencies to the appropriate
value. This change takes a maximum of five milliseconds.
10BASE-T Functionality
10BASE-T Transmit Clock Generation
The 20 MHz and 10 MHz clocks needed for 10BASE-T are synthesized from the external 25 MHz
crystal or oscillator. The PHY unit provides the transmit clock and receive clock to the internal
MAC at 2.5 MHz.
Datasheet
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