Datasheet

TUSB3410 Bootcode Flow
71
SLLS519H—January 2010 TUSB3410, TUSB3410I
Table 11−6. USB Descriptors Header (Continued)
OFFSET TYPE SIZE VALUE DESCRIPTION
40 bAlternateSetting 1 0x00 Value used to select alternate setting for the interface identified in the prior field
41 bNumEndpoints 1 0x01 Number of endpoints used by this interface (excluding endpoint zero). If this value
is zero, this interface only uses the default control pipe.
42 bInterfaceClass 1 0xFF The interface class is vendor specific.
43 bInterfaceSubClass 1 0x00
44 bInterfaceProtocol 1 0x00
45 iInterface 1 0x00 Index of string descriptor describing this interface
46 bLength 1 0x07 Size of this descriptor in bytes
47 bDescriptorType 1 0x05 ENDPOINT descriptor type
48 bEndpointAddress 1 0x01 Bit 3…0: The endpoint number
Bit 7: Direction
0 = OUT endpoint
1 = IN endpoint
49 bmAttributes 1 0x02 Bit 1…0: Transfer Type
10 = Bulk
11 = Interrupt
50 wMaxPacketSize 2 0x0040 Maximum packet size this endpoint is capable of sending or receiving when this
configuration is selected.
52 bInterval 1 0x00 Interval for polling endpoint for data transfers. Expressed in milliseconds.
53 Data Type 1 0x05 USB String descriptor
54 Data Size (low byte) 1 0x1A 26(0x1A) = 4 + 6 + 6 + 10
55 Data Size (high byte) 1 0x00
56 Check Sum 1 0x50 Checksum of data below
57 bLength 1 0x04 Size of string 0 descriptor in bytes
58 bDescriptorType 1 0x03 STRING descriptor type
59 wLANGID[0] 2 0x0409 English
61 bLength 1 0x06 Size of string 1 descriptor in bytes
62 bDescriptorType 1 0x03 STRING descriptor type
63 bString 2 ‘T’,0x00 UNICODE, ‘T’ is the first byte.
65 2 ‘I’,0x00 TI = 0x54, 0x49
67 bLength 1 0x06 Size of string 2 descriptor in bytes
68 bDescriptorType 1 0x03 STRING descriptor type
69 bString 2 ‘u’,0x00 UNICODE, ‘u’ is the first byte.
71 2 ‘C’,0x00 ‘uC’ = 0x75, 0x43
73 bLength 1 0x0A Size of string 3 descriptor in bytes
74 bDescriptorType 1 0x03 STRING descriptor type
75 bString 2 ‘3’,0x00 UNICODE, ‘T’ is the first byte.
77 2 ‘4’,0x00 ‘3410’ = 0x33, 0x34, 0x31, 0x30
79 2 ‘1’,0x00
81 2 ‘0’,0x00
83 Data Type 1 0x00 End of header
11.6.3 Autoexec Binary Firmware
If the application requires firmware loaded prior to establishing a USB connection, then the following header
can be used. The bootcode loads the firmware and releases control to the firmware directly without connecting
to the USB. However, per the USB specification requirement, any USB device should connect to the bus and
respond to the host within the first 100 ms. Therefore, if downloading time is more than 100 ms, the USB and
header speed descriptor blocks should be added before the autoexec binary firmware. Table 11−7 shows an
example of autoexec binary firmware header.