Compared to VESC the BitWizard ESC has a neat feature: no hardware (debugger/programmer) required to perform a firmware upgrade.
To flash new firmware, connect the VESC to the USB port of your computer. Then press-and-hold the button marked "BOOT". Next press-and-release the button next to it, named "RST".
Now your ESC is in firmware-download mode.
To flash the latest firmware use:
dfu-util -a 0 -D BLDC.dfu
Get/read about dfu-util at:
If you're a windows user use the software at: http://www.st.com/content/st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-programmers/stsw-stm32080.html
If you are compiling your own firmware: To generate the BLDC.dfu file, use:
dfuse-pack.py -b 0x8000000:build/BLDC_4_ChibiOS.bin BLDC.dfu
in your firmware source directory.