source code & business solutions: 2014

Intro

Find below step-by-step information on how to connect your codenvy development environment with a bitbucket repository using SSH with a SSH key generated by codenvy.

1. Codenvy (generate SSH key)

Having a project open -> window -> Preferences -> SSH keystore -> Generate key -> the aplication asks for a url: give bitbucket.org
It generates a new line in the list of SSH keystore with the host label bitbucket.org (as you gave it)
Press the view button of that line, and the SSH key will be presented to you.
Copy all the content of the message box - including the initial 'ssh-rsa' string and the final 'email@address.com'.

2. Bitbucket.org (add the key to your account)

Account -> SSH keys -> Add key
On the popup window type 'bitbucket' in the label text field, and in the key field paste the generated key from codenvy.

3. Codenvy (add a remote git repository to your project)

Git -> Remotes -> Remotes -> The remote repositories message box includes the already declared remote repositories.
Press add, and in the pop-up window, give the name 'bitbucket' in the name field and type: ssh://git@altssh.bitbucket.org:443/<accountname>/<reponame>/ as described in this page: https://confluence.atlassian.com/display/BITBUCKET/Use+the+SSH+protocol+with+Bitbucket
Where accountname is your account name in bitbucket, and reponame is your repository name in bitbucket.

More than interested in embedded platforms and microcontrollers, I acquired my 2 Raspberry pis full of enthusiasm, waiting at the end of long priority queues.
I downloaded some linux SD card images, I played with Rasbian and XBMC.
My enthusiasm faded out as I had not enough time to tinker more.
In the first months of this year (2014) I found out that Oracle was offering a training exactly on my needs. Using my preferred programming language, Java, a Raspberry pi, and some additional electronic components, a cutting edge project will educate as about embedded computing. This is the perfect chance for me to learn some things I always wanted to.
Unfortunately, I couldn't manage to follow the training, due to other running things.
But, I enjoyed their decision in Oracle to offer the material open to the public with unlimited access. Thank you guys!

Working with the training videos, I found out:

how a breadboard works
what are these breakout circuits
several configuration issues on linux
programming I/O pins of Raspberry pi using Java ME API

The most helpful tutorial on configuring the development environment with Raspberry pi and Rasbian is found here: http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/RaspberryPi_Setup/RaspberryPi_Setup.html. I found this link on the supporting material of the training course.

It's great! And it's even easier than I thought it could be.
The first hands on project was to blink a LED driven by the Raspberry pi. I found that it may be too easy, and I thought that it would be far more interesting to implement a morse code generator.
Given a message, the machine should blink the LED with Dits and Dahs, and the result would be a correctly transmitted message translated into morse code.

I found the morse code rules at: http://www.colorpilot.com/morse.html

The code for the MIDLet is as follows:

import javax.microedition.midlet.MIDlet;
/**
 *
 * @author stavros
 */
public class TestLed extends MIDlet {
   
    MorseDevice dev;
   
    @Override
    public void startApp() {
        String message = "SOS";
       
        System.out.println("Starting playing message: " + message);
        dev = new MorseDevice();
        dev.setMessage(message);
        dev.start();
    }
   
    @Override
    public void destroyApp(boolean unconditional) {
        System.out.println("Finished playing message...");
    }
}

The code for the morse machine is as follows:

import java.util.Map;

/**
 *
 * @author stavros
 */
public class MorseDevice extends Thread {
  
    private final static int UNITMS=200;
  
    private GPIOLed led;
  
    private String message;
    public void setMessage(String message) {
        this.message = message;
    }
  
    private Map<String, MorseCode[]> map = MorseCode.getMap();

    @Override
    public void run() {
        led = new GPIOLed(18);
      
        for (int i=0; i<message.length(); i++) {
            char character = message.charAt(i);
          
            if (character == ' ') {
                // space has been handled
            }
            else {
                MorseCode[] code = map.get(String.valueOf(character));
                play(code);

                if (i < message.length()-1) {
                    char nextchar = message.charAt(i+1);
                    if (nextchar == ' ') {
                        wordpause();
                    }
                    else {
                        letterpause();
                    }
                }
            }
        }
    }
  
    private void play(MorseCode[] code) {
        for (MorseCode c: code) {
            this.led.on();
            delay(c);
            this.led.off();
            delay(UNITMS/20);
        }
    }
  
    private void wordpause() {
        delay(7*UNITMS);
    }
  
    private void letterpause() {
        delay(3*UNITMS);
    }
  
    private void delay(MorseCode mc) {
        if (MorseCode.DIT.equals(mc)) {
            delay(UNITMS);
        }
        else if (MorseCode.DAH.equals(mc)) {
            delay(3*UNITMS);
        }
    }
  
    private void delay(int milliseconds) {
        try {
            sleep(milliseconds);
        }
        catch(InterruptedException ie) {
            System.out.println(ie.getMessage());
        }
    }
  
}

The morse code encoding class is as follows:

import java.util.HashMap;
import java.util.Map;
/**
 *
 * @author stavros
 */
public enum MorseCode {
    DIT,
    DAH;
   
    public static Map<String,MorseCode[]> getMap() {
        Map<String, MorseCode[]> map = new HashMap<>();
       
        map.put("A", new MorseCode[]{DIT, DAH});
        map.put("B", new MorseCode[]{DAH, DIT, DIT, DIT});
        map.put("C", new MorseCode[]{DAH, DIT, DAH, DIT});
        map.put("D", new MorseCode[]{DAH, DIT, DIT});
        map.put("E", new MorseCode[]{DIT});
        map.put("F", new MorseCode[]{DIT, DIT, DAH, DIT});
        map.put("G", new MorseCode[]{DAH, DAH, DIT});
        map.put("H", new MorseCode[]{DIT, DIT, DIT, DIT});
        map.put("I", new MorseCode[]{DIT, DIT});
        map.put("J", new MorseCode[]{DIT, DAH, DAH, DAH});
        map.put("K", new MorseCode[]{DAH, DIT, DAH});
        map.put("L", new MorseCode[]{DIT, DAH, DIT, DIT});
        map.put("M", new MorseCode[]{DAH, DAH});
        map.put("N", new MorseCode[]{DAH, DIT});
        map.put("O", new MorseCode[]{DAH, DAH, DAH});
        map.put("P", new MorseCode[]{DIT, DAH, DAH, DIT});
        map.put("Q", new MorseCode[]{DAH, DAH, DIT, DAH});
        map.put("R", new MorseCode[]{DIT, DAH, DIT});
        map.put("S", new MorseCode[]{DIT, DIT, DIT});
        map.put("T", new MorseCode[]{DAH});
        map.put("U", new MorseCode[]{DIT, DIT, DAH});
        map.put("V", new MorseCode[]{DIT, DIT, DIT, DAH});
        map.put("W", new MorseCode[]{DIT, DAH, DAH});
        map.put("X", new MorseCode[]{DAH, DIT, DIT, DAH});
        map.put("Y", new MorseCode[]{DAH, DIT, DAH, DAH});
        map.put("Z", new MorseCode[]{DAH, DAH, DIT, DIT});
       
        map.put("0", new MorseCode[]{DAH, DAH, DAH, DAH, DAH});
        map.put("1", new MorseCode[]{DIT, DAH, DAH, DAH, DAH});
        map.put("2", new MorseCode[]{DIT, DIT, DAH, DAH, DAH});
        map.put("3", new MorseCode[]{DIT, DIT, DIT, DAH, DAH});
        map.put("4", new MorseCode[]{DIT, DIT, DIT, DIT, DAH});
        map.put("5", new MorseCode[]{DIT, DIT, DIT, DIT, DIT});
        map.put("6", new MorseCode[]{DAH, DIT, DIT, DIT, DIT});
        map.put("7", new MorseCode[]{DAH, DAH, DIT, DIT, DIT});
        map.put("8", new MorseCode[]{DAH, DAH, DAH, DIT, DIT});
        map.put("9", new MorseCode[]{DAH, DAH, DAH, DAH, DIT});
       
        return map;
    }
   
}

The code for the LED is as follows:

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import jdk.dio.DeviceManager;
import jdk.dio.gpio.GPIOPin;
/**
 *
 * @author stavros
 */
public class GPIOLed {
   
    private GPIOPin pin;
   
    public GPIOLed(final int pin) {
        try {
            this.pin = DeviceManager.open(pin);
        }
        catch(Exception ioe) {
            System.out.println(ioe.getMessage());
            this.pin = null;
        }
    }
   
    public void on() {
        try {
            this.pin.setValue(true);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
   
    public void off() {
        try {
            this.pin.setValue(false);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
   
}

Finally, this is a picture of the breadboard connected with the raspberry and the green light:

source code & business solutions

Tuesday, December 9, 2014

Connecting your codenvy development environment with a bitbucket git repository

Intro

1. Codenvy (generate SSH key)

2. Bitbucket.org (add the key to your account)

3. Codenvy (add a remote git repository to your project)

Sunday, October 5, 2014

VDSL @home

Friday, September 26, 2014

Intel Edison on my hands

Morse code LED - light emitting diode - with Raspberry pi