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Compiling with a Custom Configuration

The VI firmware doesn't understand the JSON configuration file format natively, so next you have to convert it to a C++ implementation. The OpenXC Python library includes a tool that will generate the C++ for signals.cpp from your configuration file, so you still don't have to write any code.

You should already have the Python library installed from the environment setup you did earlier (and if not, run pip install openxc). Assuming the accelerator-config.json file we created is in our home directory, run this to generate a valid signals.cpp for our CAN signal:

vi-firmware/src $ openxc-generate-firmware-code --message-set ~/accelerator-config.json > signals.cpp

and then re-compile the firmware:

vi-firmware $ fab reference build
Compiling for FORDBOARD...
...
15 Compiling build/FORDBOARD/signals.o
Producing build/FORDBOARD/vi-firmware-FORDBOARD.elf
Producing build/FORDBOARD/vi-firmware-FORDBOARD.bin
Compiled successfully for FORDBOARD running under a bootloader.

Success! The compiled firmware is located at build/FORDBOARD/vi-firmware-FORDBOARD.bin. We can use the same VI re-flashing procedure that we used for a binary firmware from an automaker with our custom firmware - the process is going to depend on the VI you have, so see the list of supported VIs to find the right instructions.

There's a lot more you can do with the firmware - many more CAN signals simultaneously, raw CAN messages, diagnostic reqwuests, advanced data transformation, etc. For complete details, see the VI Firmware docs. You can find the right PLATFORM value for your VI in the VI firmware supported platforms page.