Lucent Technologies USS-720 - Manual (Page 34)

5-8 Lucent Technologies Inc.
USS-720 Instant USB Preliminary Data Sheet, Rev. 5
USB-to- IEEE 1284 Bridge September 1999
13
USB Port (continued)
Interface Descriptors
The USS-720 supports a single interface with three alternate settings.
Interface 0, Alternate Setting 0 (I0:A0)
Table 6. Interface Descriptor, I0:A0
Offset Field Size Value Description
0 bLength Byte 0x09 Size of this descriptor in bytes.
1 bDescriptorType Byte 0x04 Interface descriptor type.
2 bInterfaceNumber Byte 0x00 Zero-based value identifying the number of this interface.
3 bAlternateSetting Byte 0x00 Value used to select this alternate interface.
4 bNumEndpoints Byte 0x01 Number of endpoints used by this descriptor.
5 bInterfaceClass Byte 0x07 Printer class.
6 iInterfaceSubClass Byte 0x01 Printer subclass.
7 bInterfaceProtocol Byte 0x01 Unidirectional interface.
8 iInterface Byte 0x00 Index to string describing this interface.
Table 7. Bulk Out Endpoint Descriptor, I0:A0:E1
Offset Field Size Value Description
0 bLength Byte 0x07 Size of this descriptor in bytes.
1 bDescriptorType Byte 0x05 Endpoint descriptor type.
2 bEndpointAddress Byte 0x01 This is an Out endpoint, endpoint number 1.
3 bmAttributes Byte 0x02 This is a Bulk endpoint.
4 wMaxPacketSize Word 0x0040 Maximum data transfer size.
6 bInterval Byte 0x00 Does not apply to bulk endpoints.