Boot Loader
The actual values that can be customized are the following:
Vendor ID (default 0x1CBE)
Product ID (default 0x00FF)
Bus/Self Power (default Self Powered)
Max Power (default 0)
Device Version (default 0x110)
All strings in multiple languages
The defaults for the strings are a Manufacturer set to “Texas Instruments”, Product set to “Device
Firmware Update”, and serial number set to “1.0”.
If the application is providing a structure to the boot loader with custom values, then the first 12
bytes must contain valid data. The values in the structure that is passed to the boot loader have the
following meaning and are merged directly to the device and configuration descriptor for the boot
loader:
Byte Value
0 VID bits 7:0
1 VID bits 15:8
2 PID bits 7:9
3 PID bits 15:8
4 Device Version(BCD) bits 7:9
5 Device Version(BCD) bits 15:8
6 Power in 2mA Increments(250 maximum)
7 USB Configuration Descriptor bmAttributes (Self powered 0xC0,
Bus powered 0x80).
8-11 Pointer to the string table
The values for the custom strings are contained in a pointer at the end of the structure passed to
the boot loader. If the application wants to use the default strings, this pointer should be set to 0.
The string table provided supports custom strings for Manufacturer, Product, and Serial Number in
multiple languages. The string table is optimized to not require that a string be provided for every
language in case there is not a unique string for every language. This is most likely the case for the
Serial Number string but it could be any string that is provided.
The string table has a header that describes the number of languages provided and the language
identifiers for each followed by a set of strings for each language. Each entry in the table has a size
header that specifies the size of the string in bytes plus a byte for the size itself and a one byte tag
of USB_DTYPE_STRING(0x03). This size and ID padding is included for ease of string handling in
the boot loader and is required. It is very important for the application to provide the correct size
values because the boot loader uses these to skip through the array and find the requested strings
requested by the USB host. If these sizes are incorrect, the boot loader may fail to enumerate, so
care should be taken when building the string table. The application must provide all three strings
in the first language because these strings are treated as the default if a string is left blank in
other languages. In other languages, a string can be left blank for strings that do not change per
language. A blank entry in the table consists of a two byte entry with a byte size value of 2 followed
by the USB_DTYPE_STRING value.
The string table has the following format:
22 April 8, 2013
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