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Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
Revision 1.4 (08-19-08) 82 SMSC LAN9311/LAN9311i
DATASHEET
Chapter 7 Ethernet PHYs
7.1 Functional 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
7.1.1 PHY Addressing
Each individual PHY is assigned a unique default PHY address via the phy_addr_sel_strap
configuration strap as shown in Ta ble 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
PHY_ADDR_SEL_STRAP
VIRTUAL PHY DEFAULT
ADDRESS VALUE
PORT 1 PHY DEFAULT
ADDRESS VALUE
PORT 2 PHY DEFAULT
ADDRESS VALUE
0012
1123