Product manual

Spinpoint M9TU-USB 3.0 Product Manual REV 1.0

USB INTERFACE AND USB COMMANDS

6.4.2 Standard Descriptors

The device shall support the following standard USB descriptors:

• Device. Each USB device has one device descriptor (per USB Specification).

• Configuration. Each USB device has one default configuration descriptor, which supports at least one

interface.

• Interface. The device shall support at least one interface, known herein as the Bulk-Only Data Interface. Some

devices may support additional interfaces, to provide other capabilities.

• Endpoint. The device shall support the following endpoints, in addition to the default pipe that is required of

all USB devices:

(a) Bulk-In endpoint

(b) Bulk-Out endpoint

Some devices may support additional endpoints, to provide other capabilities. The host shall use the first

reported Bulk-In and Bulk-Out endpoints for the selected interface.

• String. The device shall supply a unique serial number.

The rest of this section describes the standard USB device, configuration, interface, endpoint, and string

descriptors for the device.

6.4.2.1 Device Descriptor

Each USB device has one device descriptor (per USB Specification). The device shall specify the device class

and subclass codes in the interface descriptor, and not in the device descriptor. (Table 6-20)

Table 6-20: Bulk Only Transport Device Descriptor

The iSerialNumber field shall be set to the index of the string descriptor that contains the serial number. The

serial number shall contain at least 12 valid digits, represented as a UNICODE string. The last 12 digits of the

serial number shall be unique to each USB idVendor and idProduct pair.

The host may generate a globally unique identifier by concatenating the 16 bit idVendor, the 16 bit idProduct

and the value represented by the last 12 characters of the string descriptor indexed by iSerialNumber. The field

iSerialNumber is an index to a string descriptor and does not contain the string itself. An example format for the

String descriptor is shown below. (Table 6-21)

Table 6-21: Example Serial Number Format