LAN9313 Datasheet, PDF (98/398 Pages) SMSC Corporation – Three Port 10/100 Managed Ethernet Switch with MII

7.2.11
7.2.12
Three Port 10/100 Managed Ethernet Switch with MII
Datasheet
LEDs
Each PHY provides LED indication signals to the GPIO/LED block of the LAN9313/LAN9313i. This
allows external LEDs to be used to indicate various PHY related functions such as TX/RX activity,
speed, duplex, or link status. Refer to Chapter 12, "GPIO/LED Controller," on page 142 for additional
information on the configuration of these signals.
Required Ethernet Magnetics
The magnetics selected for use with the LAN9313/LAN9313i should be an Auto-MDIX style magnetic,
which is widely available from several vendors. Please review the SMSC Application note 8.13
“Suggested Magnetics” for the latest qualified and suggested magnetics. A list of vendors and part
numbers are provided within the application note.
7.3
Virtual PHY
The Virtual PHY provides a basic MII management interface (MDIO) to the MII management pins per
the IEEE 802.3 (clause 22) so that a MAC with an unmodified driver can be supported as if the MAC
was attached to a single port PHY. This functionality is designed to allow easy and quick integration
of the LAN9313/LAN9313i into designs with minimal driver modifications. The Virtual PHY provides a
full bank of registers which comply with the IEEE 802.3 specification. This enables the Virtual PHY to
provide various status and control bits similar to those provided by a real PHY. These include the
output of speed selection, duplex, loopback, isolate, collision test, and auto-negotiation status. For a
list of all Virtual PHY registers and related bit descriptions, refer to Section 13.2.1, "Virtual PHY
Registers," on page 231.
7.3.1 Virtual PHY Auto-Negotiation
The purpose of the auto-negotiation function is to automatically configure the Virtual PHY to the
optimum link parameters based on the capabilities of its link partner. Because the Virtual PHY has no
actual link partner, the auto-negotiation process is emulated with deterministic results.
Auto-negotiation is enabled by setting bit 12 (VPHY_AN) of the Virtual PHY Basic Control Register
(VPHY_BASIC_CTRL) and is restarted by the occurrence of any of the following events:
„ Power-On Reset (POR)
„ Hardware reset (nRST)
„ PHY Software reset (via bit 3 of the Reset Control Register (RESET_CTL), or bit 15 of the Virtual
PHY Basic Control Register (VPHY_BASIC_CTRL))
„ Setting the Virtual PHY Basic Control Register (VPHY_BASIC_CTRL), bit 9 high (auto-neg restart)
„ Digital Reset (via bit 10 of the Reset Control Register (RESET_CTL))
„ Issuing an EEPROM Loader RELOAD command (Section 8.2.4, "EEPROM Loader," on page 113)
The emulated auto-negotiation process is much simpler than the real process and can be categorized
into three steps:
1. Bit 5 (Auto-Negotiation Complete) is set in the Virtual PHY Basic Status Register
(VPHY_BASIC_STATUS).
2. Bit 1 (Page Received) is set in the Virtual PHY Auto-Negotiation Expansion Register
(VPHY_AN_EXP).
3. The auto-negotiation result (speed and duplex) is determined and registered.
The auto-negotiation result (speed and duplex) is determined using the Highest Common Denominator
(HCD) of the Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV) and Virtual PHY
Auto-Negotiation Link Partner Base Page Ability Register (VPHY_AN_LP_BASE_ABILITY) as
specified in the IEEE 802.3 standard. The technology ability bits of these registers are ANDed, and if
there are multiple bits in common, the priority is determined as follows:
Revision 1.2 (04-08-08)
98
DATASHEET
SMSC LAN9313/LAN9313i