Firmware for some canbus boxes which are available on aliexpress.
A canbus box is a device that allows you to connect your Android device to a CAN bus
General canbus box features:
Since the adapter supports several car models and protocols, the adapter must first be configured for a specific car. To configure, the adapter must be connected to the Rx and TX lines at 38400 speed using any terminal program (putty, hyperterminal, minicom ...) Changing the configuration of the adapter is possible in debug mode. Switching to debug mode occurs when you press the corresponding keys on the keyboard:
You can also check the firmware using the emulator qemu. Below is the debug window of the firmware launched in the emulator qemu with help command "make run_qemu"