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Preliminary Data Sheet, Rev. 5 USS-720
Instant USB
September 1999 USB-to-
IEEE
1284 Bridge
Lucent Technologies Inc. 5-9
13
USB Port (continued)
Interface 0, Alternate Setting 1 (I0:A1)
Table 8. Interface Descriptor, I0:A1
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 0x01 Value used to select this alternate interface.
4 bNumEndpoints Byte 0x02 Number of endpoints used by this descriptor.
5 bInterfaceClass Byte 0x07 Printer class.
6 iInterfaceSubClass Byte 0x01 Printer subclass.
7 bInterfaceProtocol Byte 0x02 Bidirectional interface.
8 iInterface Byte 0x00 Index to string describing this interface.
Table 9. Bulk Out Endpoint Descriptor, I0:A1: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.
Table 10. Bulk In Endpoint Descriptor, I0:A1:E2
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 0x82 This is an In endpoint, endpoint number 2.
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.