Datasheet

TUSB3410 Bootcode Flow
68
SLLS519H—January 2010TUSB3410, TUSB3410I
Table 11−5. String Descriptor (Continued)
OFFSET FIELD SIZE VALUE DESCRIPTION
68 2 ‘ ’,0x00
70 2 ‘D’,0x00
72 2 ‘e‘,0x00
74 2 ‘v’,0x00
76 2 ‘I,0x00
78 2 ‘c’,0x00
80 2 ‘e’,0x00
82 bLength 1 34 (decimal) Size of string 3 descriptor in bytes
84 bDescriptorType 1 0x03 STRING descriptor type
86 bString 2 r0,0x00 UNICODE
88 2 r1,0x00 R0 to rF are BCD of SERNUM0 to
90 2 r2,0x00 SERNUM7 registers. 16 digit hex
92 2 r3,0x00 16 digit hex numbers are created from
94 2 r4,0x00 SERNUM0 to SERNUM7 registers
96 2 r5,0x00
98 2 r6,0x00
100 2 r7,0x00
102 2 r8,0x00
104 2 r9,0x00
106 2 rA,0x00
108 2 rB,0x00
110 2 rC,0x00
112 2 rD,0x00
114 2 rE,0x00
116 2 rF,0x00
11.4 External I
2
C Device Header Format
A valid header should contain a product signature and one or more descriptor blocks. The descriptor block
contains the descriptor prefix and content. In the descriptor prefix, the data type, size, and checksum are
specified to describe the content. The descriptor content contains the necessary information for the bootcode
to process.
The header processing routine always counts from the first descriptor block until the desired block number
is reached. The header reads in the descriptor prefix with a size of 4 bytes. This prefix contains the type of
block, size, and checksum. For example, if the bootcode would like to find the position of the third descriptor
block, then it reads in the first descriptor prefix, calculates the position on the second descriptor prefix based
on the size specified in the prefix. bootcode, then repeats the same calculation to find out the position of the
third descriptor block.
11.4.1 Product Signature
The product signature must be stored at the first 2 bytes within the I
2
C storage device. These 2 bytes must
match the product number. The order of these 2 bytes must be the LSB first followed by the MSB. For example,
the TUSB3410 is 0x3410. Therefore, the first byte must be 0x10 and the second byte must be 0x34.
The TUSB3410 bootcode searches the first 2 bytes of the I
2
C device. If the first 2 bytes are not 0x10 and 0x34,
then the bootcode skips the header processing.