LAN9303MI-AKZE Datasheet, PDF (111/386 Pages) SMSC Corporation – Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII

Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII
Datasheet
„ PHY Software reset (via the Virtual PHY Reset (VPHY_RST) bit of the Reset Control Register
(RESET_CTL), or the Reset (VPHY_RST) bit of the Virtual PHY Basic Control Register
(VPHY_BASIC_CTRL))
„ Setting the Virtual PHY Basic Control Register (VPHY_BASIC_CTRL), Restart Auto-Negotiation
(VPHY_RST_AN) bit high
„ Digital Reset (via the Digital Reset (DIGITAL_RST) bit of the Reset Control Register (RESET_CTL))
„ Issuing an EEPROM Loader RELOAD command (Section 8.4, "EEPROM Loader," on page 121)
The emulated auto-negotiation process is much simpler than the real process and can be categorized
into three steps:
1. The Auto-Negotiation Complete bit is set in the Virtual PHY Basic Status Register
(VPHY_BASIC_STATUS).
2. The Page Received bit is set in the Virtual PHY Auto-Negotiation Expansion Register
(VPHY_AN_EXP).
3. The auto-negotiation result (speed, duplex, and pause) 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:
„ 100Mbps Full Duplex (highest priority)
„ 100Mbps Half Duplex
„ 10Mbps Full Duplex
„ 10Mbps Half Duplex (lowest priority)
For example, if the full capabilities of the Virtual PHY are advertised (100Mbps, Full Duplex), and if
the link partner is capable of 10Mbps and 100Mbps, then auto-negotiation selects 100Mbps as the
highest performance mode. If the link partner is capable of half and full-duplex modes, then auto-
negotiation selects full-duplex as the highest performance operation. In the event that there are no bits
in common, an emulated Parallel Detection is used.
The Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV) defaults to having all four
ability bits set. These values can be reconfigured via software. Once the auto-negotiation is complete,
any change to the Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV) will not take
affect until the auto-negotiation process is re-run. The emulated link partner default advertised abilities
in the Virtual PHY Auto-Negotiation Link Partner Base Page Ability Register
(VPHY_AN_LP_BASE_ABILITY) are dependant on the P0_DUPLEX pin and the duplex_pol_strap_0
and speed_strap_0 configuration straps as described in Table 13.7 of Section 13.2.6.6, "Virtual PHY
Auto-Negotiation Link Partner Base Page Ability Register (VPHY_AN_LP_BASE_ABILITY)," on
page 190. Neither the Virtual PHY or the emulated link partner support next page capability, remote
faults, or 100BASE-T4.
Note: The P0_DUPLEX, duplex_pol_strap_0, and speed_strap_0 inputs are considered to be static.
Auto-negotiation is not automatically re-evaluated if these inputs are changed.
If there is at least one common selection between the emulated link partner and the Virtual PHY
advertised abilities, then the auto-negotiation succeeds, the Link Partner Auto-Negotiation Able bit of
the Virtual PHY Auto-Negotiation Expansion Register (VPHY_AN_EXP) is set, and the technology
ability bits in the Virtual PHY Auto-Negotiation Link Partner Base Page Ability Register
(VPHY_AN_LP_BASE_ABILITY) are set to indicate the emulated link partners abilities.
Note: For the Virtual PHY, the auto-negotiation register bits (and management of such) are used by
the PMI. So the perception of local and link partner is reversed. The local device is the PMI,
SMSC LAN9303M/LAN9303Mi
111
DATASHEET
Revision 1.5 (07-08-11)