Blinking an LED with Java on the Intel Edison
05 February 2016

I have been keen to use Java on the Intel Edison since hearing that the Edison supports Java. At the time of writing this, I could not find much information on how to use Java with the Edison. So I decided to try and get a simple LED blink program going. While a blink program is very simple, the hello world of hardware, it thought me the important bits about using the Edison with Java.

Here is the blink program in action:

And here is the blink program's code:

import mraa.Gpio;

public class EdisonTest {

    static {
        try {
            System.loadLibrary("mraajava");
        } catch (UnsatisfiedLinkError e) {
            System.err.println("Native code library failed to load.");
            System.exit(1);
        }
    }

    public static void main(String[] args) throws InterruptedException {
        Gpio gpio = new Gpio(11);
        gpio.dir(Dir.DIR_OUT);
        int state = 1;

        while (true){
            gpio.write(state);
            state = (state==1?0:1); 
            Thread.sleep(1000);
        }
    } 

}

The command to run the program is java -Djava.library.path=/usr/lib/java/ -jar EdisonTest.jar. I used WinSCP to put the EdisonTest.jar and its lib folder into /home/root/ (where I ran the program from).

If you get any problems check that your manifest file includes the lib folder. And that the lib folder includes the mraa.jar. You can download the mraa.jar and UPM jars from Intel.