JABI

JABI (Just Another Bridge Interface) makes creating and deploying bridge devices that provide RPC to common microcontroller peripherals simple.

Architecture

Interfaces are the available methods by which a single client may connect. Multiple interfaces running concurrently is supported. The following interfaces are currently supported.

• USB
• UART

Microcontroller peripherals are made available over each interface via a custom basic RPC. Each interface listens for request packets and dispatches them to the appropriate peripheral. Multiple instances of each peripheral type is supported. The following peripherals are currently supported.

• Metadata
• CAN (FD)
• LIN
• SPI controller
• I2C controller
• UART
• GPIO
• PWM
• ADC
• DAC

Clients connect to the microcontroller over any one of the interfaces. The following clients are supported.

• C++
• Python - pip install pyjabi
• gRPC
• Rust - cargo add jabi

Setup

Firmware

Follow Zephyr's Getting Started Guide to get dependencies installed. Then create a new workspace using this repo. We'll create it under jabi, but you can use whatever you want.

west init -m https://github.com/dragonlock2/JABI.git jabi
cd jabi && west update

To port any board, you'll need the following. See firmware/boards for examples.

• Zephyr board definition. See Zephyr's Board Porting Guide for help.
• firmware/boards/<board>.conf - enable device drivers and any desired settings
• firmware/boards/<board>.overlay - selects available interfaces and peripherals

Now compile and flash the firmware.

west build -b <board>
west flash

Dependencies

If you want to build from source, you may need to install a few dependencies.

• macOS
  • brew install git cmake autoconf automake libtool libusb grpc openssl
• Linux
  • apt install git cmake autotools-dev autoconf libtool libusb-1.0-0-dev libssl-dev
  • Install grpc from source.
• Windows
  • Install Visual Studio C++ for its C++ compiler.
  • Use winget to install git and CMake.
  • Use vcpkg to install libusb, gRPC, OpenSSL, and getopt.
• Windows (MSYS2/MinGW) (experimental)
  • Install MSYS2 to install the following packages.
  • pacman -S mingw-w64-ucrt-x86_64-gcc git mingw-w64-ucrt-x86_64-cmake mingw-w64-ucrt-x86_64-autotools mingw-w64-ucrt-x86_64-libusb mingw-w64-ucrt-x86_64-grpc
    • If you're not on x86_64, your exact package names may be different.

C++

C++ support is provided as a CMake library and can be added to any CMake project using add_subdirectory. An example project is in examples/cpp.

Python

A Python library is published on PyPI. For the latest changes, it can be built and installed locally by running the following. An example using it is in examples/python.

pip install clients/python

gRPC

Protobuf definitions are located in jabi.proto. grpc-server is a reference server implementation that bridges one device to a network and can handle parallel requests. It provides various arguments for selecting the desired device. An example client is in examples/grpc-client.

Rust

A Rust crate is published on crates.io. For the latest changes, it can be added locally. An example project is in examples/rust.

TODO

The following gRPC clients.

• Google Flutter cross-platform app

Fun things to look into one day.

• Better documentation...
• Unit testing...
• Alternative functions for pins
• Move to Thrift for RPC (natively supported in Zephyr!)
  • Network (Ethernet, WiFi) support
• BLE support
• USB Linux drivers to show up under /dev
• USB HS dev board for comparable performance to STLINK-V3