In order to perform firmware updates with the OpenBLT from SD-card, double-check that the file system 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 SD-card are configured to look for a 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 STM32-E407 demo:

static const blt_char firmwareFilename[] = "/demoprog_olimex_stm32e407.srec";

To prepare the SD-card and start the update procedure, perform the following steps:

1. Insert the SD-card 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. Insert the SD-card into the card holder on the microcontroller board.
3. Reset the microcontroller to start the firmware update. Once done, the newly programmed firmware is automatically started.

Note that the bootloader demo is configured to output log messages to a serial terminal. This enables you to view the progress of the firmware update with a terminal program such as Putty. The communication speed is typically 57600 bits/sec. Additionally, the log messages are written to a file called bootlog.txt on the SD-card, which can optionally be checked for verification purposes.