LAN9312 datasheet(82/458 Pages) SMSC

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High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

Datasheet

Revision 1.2 (04-08-08)

SMSC LAN9312

DATASHEET

Chapter 7 Ethernet PHYs

7.1

Functional Overview

The LAN9312 contains three PHYs: Port 1 PHY, Port 2 PHY and a Virtual PHY. The Port 1 & 2 PHYs

are identical in functionality and each connect their corresponding Ethernet signal pins to the switch

fabric MAC of their respective port. These PHYs interface with their respective MAC via an internal MII

interface. The Virtual PHY provides the virtual functionality of a PHY and allows connection of the Host

MAC to port 0 of the switch fabric as if it was connected to a single port PHY. All PHYs comply with

the IEEE 802.3 Physical Layer for Twisted Pair Ethernet and can be configured for full/half duplex 100

Mbps (100BASE-TX) or 10Mbps (10BASE-T) Ethernet operation. All PHY registers follow the IEEE

802.3 (clause 22.2.4) specified MII management register set and can be configured indirectly via the

Host MAC, or directly via the memory mapped Virtual PHY registers. Refer to Section 14.4, "Ethernet

PHY Control and Status Registers" for details on the Ethernet PHY registers.

The LAN9312 Ethernet PHYs are discussed in detail in the following sections:

Section 7.2, "Port 1 & 2 PHYs," on page 83

Section 7.3, "Virtual PHY," on page 96

7.1.1

PHY Addressing

Each individual PHY is assigned a unique default PHY address via the phy_addr_sel_strap

configuration strap as shown in Table 7.1. In addition, the Port 1 PHY and Port 2 PHY addresses can

be changed via the PHY Address (PHYADD) field in the Port x PHY Special Modes Register

(PHY_SPECIAL_MODES_x). For proper operation, all LAN9312 PHY addresses must be unique. No

check is performed to assure each PHY is set to a different address. Configuration strap values are

latched upon the de-assertion of a chip-level reset as described in Section 4.2.4, "Configuration

Straps," on page 40.

Table 7.1 Default PHY Serial MII Addressing

PHY_ADDR_SEL_STRAP

VIRTUAL PHY DEFAULT

ADDRESS VALUE

PORT 1 PHY DEFAULT

ADDRESS VALUE

PORT 2 PHY DEFAULT

ADDRESS VALUE

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