In order to perform firmware updates with the OpenBLT from a USB memory stick connected to a board's USB Host connector, double-check that the file system is configured in “blt_conf.h”. The following macro should have a value of 1. If this macro did not yet have a value of 1, the bootloader should be rebuild after making the change.

#define BOOT_FILE_SYS_ENABLE            (1)

The demo bootloaders that support firmware updates from a USB memory stick are configured to look for an S-record firmware filename with a predetermined name in the root directory on the SD-card. The filename is configured as a constant character array firmwareFilename[] in hooks.c. Here is the example for the STM32F723 Discovery kit demo:

static const blt_char firmwareFilename[] = "/demoprog_stm32f723.srec";

To prepare the USB memory stick and start the update procedure, perform the following steps:

1. Insert the USB memory stick into your PC and store the firmware file (as specified by firmwareFilename[]) in its root directory. For the demo programs, you can find this file in the “.\Prog\bin\” directory.
2. Attach the USB memory stick to the board's USB Host connector. Note that a USB OTG to USB A female cable adapter might be needed.
3. Reset the microcontroller to start the firmware update. Once done, the newly programmed firmware is automatically started.