jhwbus

Java hardware bus access for Linux

A simple, thin JNI based Java library to access simple hardware buses (for e.g. I2C) from Java on Linux. The library jar brings along the native library (libjhwbus.so) and dynamically loads it at runtime. Since Linux only supports simple hardware buses directly on ARM, this library is only supported for Linux on ARM machines.

Currently, supports the following hardware buses:

• I2C/SMBUS - Linux I2C

Building

The JNI library is written in C and uses the i2c-dev interface to access the I2C bus. The library is built using the gcc compiler.

The default ./gradlew build task will build and package the library into a jar file.

On a native Linux OS (running on an ARM machine), the build task can be run directly. On non-Linux OS, the build task can be run in a containerized environment using Docker.

The Dockerfile used for the containerized build is available here

Requirements

On Linux

• Java JDK8
• gcc
• libi2c-dev - sudo apt-get install libi2c-dev

Ensure that the environment variable JAVA_HOME is defined and points the Java installation.

On non-Linux (macos)

• Container runtime like Docker Desktop or Colima

• docker cli - on macos can be installed using brew install docker

Since we need to build the native library for ARM architecture, the container runtime has to either run on an ARM machine or support ARM emulation.

Commands

./gradlew : Generates a jar with the native library included in build/libs

The default docker-cli context used is colima. However, this can be overridden using the -PdockerContext= CLI flag.

Using

The library is published to GitHub Packages and can be included in the project using the following build.gradle configuration:

repositories {
    maven {
        name = "GitHubPackages-jhwbus"
        url = uri("https://maven.pkg.github.com/jhwbus/jhwbus")
    }
}

dependencies {
    implementation 'io.github.jhwbus:jhwbus:1.2.0'
}

License

BSD 3-Clause License

See LICENSE file.