Boot Loader
DFU_CMD_BIN By default, data returned in response to a DFU_UPLOAD request includes an
8-byte DFU_CMD_PROG prefix structure. This ensures that an uploaded image
can be directly downloaded again without the need to further wrap it but, in
cases where pure binary data is required, can be awkward. The DFU_CMD_BIN
command allows the upload prefix to be disabled or enabled under host control.
The format of the command is as follows:
uint8_t pui8Data[8];
pui8Data[0] = DFU_CMD_BIN (0x06)
pui8Data[1] = 0x01 to disable upload prefix, 0x00 to enable
pui8Data[2] = Reserved - set to 0x00
pui8Data[3] = Reserved - set to 0x00
pui8Data[4] = Reserved - set to 0x00
pui8Data[5] = Reserved - set to 0x00
pui8Data[6] = Reserved - set to 0x00
pui8Data[7] = Reserved - set to 0x00
DFU_CMD_RESET This command may be sent to the USB boot loader to cause it to perform a
soft reset of the board. This reboots the system and, assuming that the main
application image is present, runs the main application. Note that a reboot also
takes place if a firmware download operation completes and the host issues a
USB reset to the DFU device.
The format of the command is as follows:
uint8_t pui8Data[8];
pui8Data[0] = DFU_CMD_RESET (0x07)
pui8Data[1] = Reserved - set to 0x00
pui8Data[2] = Reserved - set to 0x00
pui8Data[3] = Reserved - set to 0x00
pui8Data[4] = Reserved - set to 0x00
pui8Data[5] = Reserved - set to 0x00
pui8Data[6] = Reserved - set to 0x00
pui8Data[7] = Reserved - set to 0x00
2.3.5 Customizing the USB Device Firmware Upgrade
The USB boot loader provides a method to pass a set of custom values to the boot loader when
called from a running application. When the USB boot loader is entered because the flash was
empty, the boot ROM offers no customization and provides generic “Texas Instruments” and “Device
Firmware Update” strings to the host as identifiers. The USB boot loader is called by an application
via a call to ROM_UpdateUSB(), which takes a single pointer as an argument that is a pointer to
an array containing the values that the boot loader uses for customization. This pointer can also be
0 to indicate that the application wishes to use the defaults provided by the ROM boot loader. The
application can place the customization structure anywhere in flash or SRAM.
April 8, 2013 21
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