Intel GD82559ER 6.2 10BASE-T Functionality, 6.1.4 100BASE-TX Collision Detection, Link Integrity

Networking Silicon — GD82559ER

6.1.4100BASE-TX Collision Detection

100BASE-TX collisions in half duplex mode only are detected similarly to 10BASE-T collision detection, via simultaneous transmission and reception.

6.1.5100BASE-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.

6.1.5.1Link 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.

6.1.5.2Auto-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).

6.1.6Auto 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.

6.210BASE-T Functionality

6.2.110BASE-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 41