Bulldog - Java GPIO Library

Table of Contents

• Summary
• Usage
  • Maven
  • Example
• Building Bulldog (x86, x86_64)
• Building Bulldog (ARM)
• Continuous Integration
• Contribution Guidelines

Summary

Bulldog is a Java library providing Java (IoT) Developers with GPIO and low-level IO capabilities of embedded linux platforms (RaspberryPi, CubieBoard, BeagleBoneBlack).

Bulldog library is a part of the Silverspoon IoT Platform: http://silverspoon.io.

Bulldog currently supports the following features:

• Digital Input/Output on Pins (GPIOs)
• Native Interrupts via epoll (easily usable on DigitalInputs)
• Native PWM, ADC
• I2C, SPI
• All UARTs (including dynamic setup via capemgr on request)
• A few devices: Simple button API, Incremental Rotary Encoder, Servos, LCD, ...

Usage

Maven

Stable versions are synced with Maven Central. You just need to add a dependency to appropriate board implementation and Bulldog will automatically select the correct platform implementation:

<dependencies>
  <dependency>
    <groupId>io.silverspoon</groupId>
    <artifactId>bulldog-board-${board-name}</artifactId>
    <version>${version.bulldog}</version>
  </dependency>
</dependencies>

To use our development (SNAPSHOT) versions you need to add the following repository to your settings.xml:

<repositories>
  <repository>
    <id>sonatype-public-repository</id>
    <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
    <snapshots>
      <enabled>true</enabled>
    </snapshots>        
  </repository>
</repositories>

Example

The following steps can all be performed on your target device (e.g. RaspberryPi).

• Connect a LED diode to your RaspberyPi (you can follow this tutorial).

• Create new maven project and add an appropriate maven dependency:

<dependencies>
  <dependency>
    <groupId>io.silverspoon</groupId>
    <artifactId>bulldog-board-raspberrypi</artifactId>
    <version>0.2.1</version>
  </dependency>
</dependencies>

• Author the following code (You can find the example also in here:

import io.silverspoon.bulldog.core.gpio.DigitalOutput;
import io.silverspoon.bulldog.core.platform.Board;
import io.silverspoon.bulldog.core.platform.Platform;
import io.silverspoon.bulldog.core.util.BulldogUtil;
import io.silverspoon.bulldog.raspberrypi.RaspiNames;
  
public class BulldogLED {
  
  public static void main(String[] args) {
    //Detect the board we are running on
    Board board = Platform.createBoard();
    
    //Set up a digital output
    DigitalOutput output = board.getPin(RaspiNames.P1_11).as(DigitalOutput.class);

    // Blink the LED
    output.high();
    BulldogUtil.sleepMs(1000);
    output.low();
    }
}

• Configure maven-exec-plugin

<build>
  <plugins>
    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>exec-maven-plugin</artifactId>
      <version>1.3.2</version>
      <configuration>
        <mainClass>com.example.BulldogLED</mainClass>
      </configuration>
    </plugin>
  </plugins>
</build>

• Compile & execute:

mvn clean package
mvn exec:java

• If you have done everything well, your LED diode should come on, and after 1 second go off again.
• Please note that the JVM must be started with root privileges or user need to be in appropriate group for /dev/mem access e.g. kmem

Note: For more see bulldog-examples project.

Building Bulldog (x86, x86_64)

Prerequisites

• ARM C/C++ Cross Compiler (4.8+)
• Maven 3+

Fedora (20+)

sudo yum install glibc-devel.i686
sudo yum install gcc-arm-linux-gnu

Ubuntu (13.04+)

sudo apt-get install gcc-4.8-arm-linux-gnueabihf

###Build

Fedora (default)

mvn clean install

Ubuntu - need to overide compiler/linker binary:

mvn clean install -Dcompiler.exec=arm-linux-gnueabihf-gcc-4.8 -Dlinker.exec=arm-linux-gnueabihf-ld

Building Bulldog (ARM)

Prerequisites

• ARM C/C++ Compiler (4.8+)
• Maven 3+

Raspbian

sudo apt-get install gcc-4.8

Build

mvn clean install -Pnative-compile

Continuous Integration

CI server hosted on Travis-ci.org:

Contribution Guidelines

• If you find a bug, or have a feature request you think we should consider, please report it here.
• We use gitflow as a development workflow, so If you want to contribute to our code base create your own fork & send a pull request to the devel branch or ask to join our community to be able to commit directly to devel branch.