TUSB3410_10 Datasheet, PDF (73/98 Pages) Texas Instruments – USB to Serial Port Controller

TUSB3410 Bootcode Flow
11.3.3 Interface Descriptor
The interface descriptor provides the number of endpoints supported by this interface as well as interface
class, subclass, and protocol.
The bootcode supports only one endpoint and use its own class. Table 11−3 lists the interface descriptor.
OFFSET
(decimal)
0
1
2
FIELD
bLength
bDescriptorType
bInterfaceNumber
SIZE
1
1
1
3
bAlternateSetting
1
4
bNumEndpoints
1
5
bInterfaceClass
1
6
bInterfaceSubClass 1
7
bInterfaceProtocol
1
8
iInterface
1
Table 11−3. Interface Descriptor
VALUE
DESCRIPTION
9
4
0
0
1
0xFF
0
0
0
Size of this descriptor in bytes
Interface descriptor type
Number of interface. Zero-based value identifying the index in the array of concurrent
interfaces supported by this configuration.
Value used to select alternate setting for the interface identified in the prior field
Number of endpoints used by this interface (excluding endpoint zero). If this value is
zero, this interface only uses the default control pipe.
The interface class is vendor specific.
Index of string descriptor describing this interface
11.3.4 Endpoint Descriptor
The endpoint descriptor provides the type and size of communication pipe supported by this endpoint.
The bootcode supports only one output endpoint with the size of 64 bytes in addition to control endpoint 0
(required by all USB devices). Table 11−4 lists the endpoint descriptor.
OFFSET
(decimal)
0
1
2
3
4
6
FIELD
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize
bInterval
Table 11−4. Output Endpoint1 Descriptor
SIZE VALUE
DESCRIPTION
1
7
Size of this descriptor in bytes
1
5
Endpoint descriptor type
1
0x01 Bit 3…0: The endpoint number
Bit 7: Direction
0 = OUT endpoint
1 = IN endpoint
1
2
Bit 1…0: Transfer type
10 = Bulk
11 = Interrupt
2
64
Maximum packet size this endpoint is capable of sending or receiving when this
configuration is selected.
1
0
Interval for polling endpoint for data transfers. Expressed in milliseconds.
11.3.5 String Descriptor
The string descriptor contains data in the unicode format. It is used to show the manufacturers name, product
model, and serial number in human readable format.
The bootcode supports three strings. The first string is the manufacturers name. The second string is the
product name. The third string is the serial number. Table 11−5 lists the string descriptor.
66 TUSB3410, TUSB3410I
SLLS519H—January 2010