LAN9353 Datasheet, PDF (365/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
External MAC loopback is enabled when the Loopback (VPHY_LOOPBACK) bit of the Port x Virtual PHY Basic Control
Register (VPHY_BASIC_CTRL_x) is set. Transmissions from the external MAC are not sent to the Switch Fabric.
Instead, they are looped back onto the receive path. Transmissions from the Switch Fabric are ignored.
Switch Fabric loopback is enabled when the Switch Loopback bit of the Port x Virtual PHY Special Control/Status Reg-
ister (VPHY_SPECIAL_CONTROL_STATUS_x) is set. Transmissions from the Switch Fabric are not sent to the exter-
nal MAC. Instead, they are looped back internally onto the receive path. Transmissions from the external MAC are
ignored. An internal collision signal to the Switch Fabric is available and is asserted when the Switch Collision Test bit
is set. Switch Fabric loopback occurs regardless of the setting of the Isolate (VPHY_ISO) bit.
13.3 Port 2 Data Path
The MII Data Interface is used to connect the Switch Fabric port to Physical PHY B.
13.3.1 PORT 2 INTERNAL PHY MODE
When operating in Internal PHY mode, the Switch Fabric MAC outputs are routed to internal PHY B. Similarly, the Switch
Fabric MAC inputs are sourced from internal PHY B. The duplex of the Switch Fabric MAC is controlled by the PHY.
 2015 Microchip Technology Inc.
DS00001925A-page 365