Product manual

Spinpoint M9TU-USB 3.0 Product Manual REV 1.0
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USB INTERFACE AND USB COMMANDS
100 mA, then if the device switches to being bus-powered, it must return to the Address state. Self-powered hubs
that use V
BUS to power the Hub Controller are allowed to remain in the Configured state if local power is lost.
A hub port must be powered in order to detect port status changes, including attach and detach. Bus powered
hubs do not provide any downstream power until they are configured, at which point they will provide power as
allowed by their configuration and power source. A USB device must be able to be addressed within a specified
time period from when power is initially applied. After an attachment to a port has been detected, the host may
enable the port, which will also reset the device attached to the port.
6.3.6.1.3 Default
After the device has been powered, it must not respond to any bus transactions until it has received a reset from
the bus. After receiving a reset, the device is then addressable at the default address. When the reset process is
complete, the USB device is operating at the correct speed (i.e., low-/full-/highspeed).
The speed selection for low- and full-speed is determined by the device termination resistors. A device that is
capable of high-speed operation determines whether it will operate at high-speed as a part of the reset process A
device capable of high-speed operation must reset successfully at full-speed when in an electrical environment
that is operating at full-speed. After the device is successfully reset, the device must also respond successfully to
device and configuration descriptor requests and return appropriate information. The device may or may not be
able to support its intended functionality when operating at full-speed.
6.3.6.1.4 Address
All USB devices use the default address when initially powered or after the device has been reset. Each USB
device is assigned a unique address by the host after attachment or after reset. A USB device maintains its
assigned address while suspended.
A USB device responds to requests on its default pipe whether the device is currently assigned a unique address
or is using the default address.
6.3.6.1.5 Configured
Before a USB device’s function may be used, the device must be configured. From the device’s perspective,
configuration involves correctly processing a SetConfiguration () request with a non-zero configuration value.
Configuring a device or changing an alternate setting causes all of the status and configuration values associated
with endpoints in the affected interfaces to be set to their default values. This includes setting the data toggle of
any endpoint using data toggles to the value DATA0.
6.3.6.1.6 Suspended
In order to conserve power, USB devices automatically enter the Suspended state when the device has observed
no bus traffic for a specified period. When suspended, the USB device maintains any internal status, including its
address and configuration.
All devices must suspend if bus activity has not been observed for the length of time. Attached devices must be
prepared to suspend at any time they are powered, whether they have been assigned a non-default address or are
configured. Bus activity may cease due to the host entering a suspend mode of its own. In addition, a USB device
shall also enter the Suspended state when the hub port it is attached to is disabled. This is referred to as selective
suspend.
A USB device exits suspend mode when there is bus activity. A USB device may also request the host to exit
suspend mode or selective suspend by using electrical signaling to indicate remote wakeup. The ability of a
device to signal remote wakeup is optional. If a USB device is capable of remote wakeup signaling, the device
must support the ability of the host to enable and disable this capability. When the device is reset, remote wakeup
signaling must be disabled.
6.3.6.1.7 Bus Enumeration
Before an application can communicate with a device, the host needs to learn about what transfer types
and endpoint the device support. The host also must assign an address to the device (Figure 6-29)
When a USB device is attached to or removed from the USB, the host uses a process known as bus
enumeration to identify and manage the device state changes necessary. When a USB device is attached to a
powered port, the following actions are taken: