In order to perform firmware updates with the OpenBLT through the UART communication interface, double-check that this communication interface 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_COM_UART_ENABLE            (1)

The Microboot utility needs to be configured to connect to the correct COM-port and to communication at the correct baudrate:

• Start Microboot by double-clicking “\Host\MicroBoot.exe”.
• Click the “Settings”-button and select “OpenBLT using UART” from the dropdown box.
• Click the “Options”-button to configure the communication parameters.
  • Select the PC's COM-port that the board is connected to.
  • Set the baudrate to the value specified by macro BOOT_COM_UART_BAUDRATE in “blt_conf.h”. Typically, this is 57600 bits/sec for the demo programs.

Once you saved the settings by clicking the “OK”-button twice, Microboot is now ready for action!

After building your user program, its S-record formatted firmware file can be downloaded to the remaining flash memory using the bootloader. In Microboot click the “Browse”-button and select your user program's firmware file. For the demo programs, this one is located in the “.\Prog\bin\” directory. Once the firmware file was selected, the download should automatically start.

Once the download completed, the newly programmed software will be started by the bootloader. For the demo program's you can verify this by checking that the LED blinks. Congratulations! That's all there is to using the bootloader.

Depending on the configuration of the bootloader, there might be a delay between a system reset and the actual start of the user program. This is needed by design for the bootloader's backdoor functionality. Check configurable BACKDOOR_ENTRY_TIMEOUT_MS in “blt_conf.h” for the exact delay time.