Specifications

TH230/TH230+ Programmers Guide
237
Interface Descriptors
The interface descriptor describes a specific interface provided by the associated
configuration. A configuration provides one or more interfaces, each with its own
endpoint descriptors describing a unique set of endpoints within the configuration. An
interface descriptor is always returned as part of a configuration descriptor. It cannot be
accessed directly with a Get or Set Descriptor request.
An interface may include alternate settings that allow the endpoints and/or their
characteristics to be varied after the device has been configured. The default setting for an
interface is always alternate setting zero.
The TH230 printer provides two interfaces: the Firmware Upgrade interface (DFUX) and
the Printer interface. A multi-interface device is called composite device.
Interface 0 Descriptor (Printer)
This interface is used as printer class interface for transferring data to and from the device.
From the systems point of view this interface stands for the printer device so the used
printer class driver will be bind to this interface.
Offset Field Size Value Description
0 bLength 1 09h Size of this descriptor, in bytes
1 bDescriptorType 1 04h INTERFACE descriptor type
2 blnterfaceNumber 1 00h Number of this interface
3 bAltemateSetting 1 00h Alternate setting. Must be zero
4 bNumEndpoints 1 02h Number of used endpoint (except EP0)
5 bInterfaceClass 1 07h Base class for printers
6 bInterfaceSubClass 1 01h Subclass code for printer devices
7 bInterfaceProtocol 1 02h Bi-directional printer interface
8 iInterface 1 Index Index of string descriptor (see 1.1.1)
Interface 1 Descriptor (DFUX)