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Spinpoint M8U-Internal Product Manual REV 3.4
60
INSTALLATION
Table 6-4: Visible Device States
6.3.6.1.1 Attatched
A USB device may be attached or detached from the USB. The state of a USB device when it is detached
from the USB is not defined by this specification. This specification only addresses required operations and
attributes once the device is attached.
6.3.6.1.2 Powered
USB devices may obtain power from an external source and/or from the USB through the hub to which they
are attached. Externally powered USB devices are termed self-powered. Although self-powered devices may
already be powered before they are attached to the USB, they are not considered to be in the Powered state
until they are attached to the USB and V
BUS is applied to the device.
A device may support both self-powered and bus-powered configurations. Some device configurations
support either power source. Other device configurations may be available only if the device is self powered.
Devices report their power source capability through the configuration descriptor. The current power source is
reported as part of a device’s status. Devices may change their power source at any time, e.g., from self- to
bus-powered. If a configuration is capable of supporting both power modes, the power maximum reported for