LAN9500 Datasheet, PDF (98/213 Pages) SMSC Corporation – USB 2.0 to 10/100 Ethernet Controller Promiscuous mode

LAN950x
Note 1: It is not possible to transition from SUSPEND2 to NORMAL Configured if SUSPEND2 was entered via a
transition from NORMAL Unconfigured.
2: When the device is bus powered, VBUS_DET is tied to 1b. Therefore, the UNPOWERED state only has
meaning for self powered operation.
5.11.1 UNPOWERED STATE
The UNPOWERED state provides a mechanism for the device to conserve power when VBUS_DET is not connected
and the device is self powered.
The device may initially enter the UNPOWERED state when a POR occurs and USB power is not detected. This state
persists until the VBUS_DET is asserted. The UNPOWERED state is alternatively entered whenever VBUS_DET deas-
serts.
In order to make the LAN950x fully operational, the Host must configure the device, which places it in the NORMAL
Configured state.
5.11.2 NORMAL STATE
The NORMAL state is the fully functional state of the device. The are two flavors of the NORMAL state, NORMAL Con-
figured and NORMAL Unconfigured. In the Configured variation, all chip subsystem modules are enabled. The Uncon-
figured variation has only a subset of the modules enabled. The reduced functionality allows for power savings.
This NORMAL state is entered by any of the following methods.
• A system reset and VBUS_DET is asserted.
• The device is in the UNPOWERED state and VBUS_DET is asserted.
• The device is suspended and the Host issues resume signaling.
• The device is suspended and a wake event is detected.
5.11.2.1 Unconfigured
Upon initially entering the NORMAL state, the device is unconfigured. The device transitions to the NORMAL Configured
state upon the Host completion of the USB configuration.
It is possible for the device to be deconfigured by the Host after being placed in the NORMAL configured state, via a
set_configuration command. In this case, the CPM must place the device back into the NORMAL Unconfigured state.
5.11.2.2 Reset Operation
After a system reset, the device is placed into the NORMAL Unconfigured state. When in the NORMAL state, the
READY bit in the Power Management Control Register (PMT_CTL) is set. This READY bit is useful to the Host after a
USB reset occurs. In this case, it indicates that the values in the EEPROM have been completely loaded.
5.11.2.3 Suspend Operation
When returning to the NORMAL state from the SUSPEND state, the USB context is maintained. After entering the NOR-
MAL state, the READY bit in the PMT_CTL register is asserted.
Note: If the originating suspend state is SUSPEND2, the Host is required to reinitialize the Ethernet PHY regis-
ters.
5.11.3 SUSPEND STATES
The SUSPEND state is entered after the USB Host suspends the device. The LAN950x family features four (Note 5-3)
variations of the USB SUSPEND state. Each state offers different options in terms of power consumption and wakeup
support.
A SUSPEND state is entered via a transition from the NORMAL state. The SUSPEND_MODE field in the Power Man-
agement Control Register (PMT_CTL), indicates which SUSPEND state is to be used. The Host sets the value of this
field to select the desired suspend state, then sends suspend signaling. A transfer back to the NORMAL state occurs
when the Host sends resume signaling or a wakeup event is detected.
The device can be suspended from the NORMAL Unconfigured state. In this scenario, it is only possible to transition to
the SUSPEND2 state. Subsequent resume signaling or a wakeup event will cause the device to transition back to the
NORMAL Unconfigured state.
DS00001875A-page 98
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