Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface

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Chapter 7 Ethernet PHYs

7.1Functional Overview

The LAN9311/LAN9311i 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 LAN9311/LAN9311i 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

7.1.1PHY 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 LAN9311/LAN9311i 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

 

VIRTUAL PHY DEFAULT

PORT 1 PHY DEFAULT

PORT 2 PHY DEFAULT

PHY_ADDR_SEL_STRAP

ADDRESS VALUE

ADDRESS VALUE

ADDRESS VALUE

 

 

 

 

0

0

1

2

 

 

 

 

1

1

2

3

 

 

 

 

Revision 1.4 (08-19-08)

82

SMSC LAN9311/LAN9311i

 

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