Today I tested out the new aerofoil on the rubber powered Aerocrafts flying dove, (AC031), and it’s performance is satisfactory.

I recently purchased an Acer Aspire 4937G, laptop. The configuration is as below.

• ntel Core2 Duo T7450 2.13GHz
• 4GB DDR3 Ram
• Nvidia G105M Graphics Adapter
• 14″ Glossy Display
• 320GB Harddisk (Though the usable portion is around 270GB)

This laptop comes branded as a Multimedia Laptop which is supposed to have built in DVD player application (embeded), But I couldn’t yet discover how to get it to work, without Vista. (I may have corrupted the specific application partition (which has a embeded XP) when installing linux as it gives a HAL error when I load it through the GRUB).

The ubuntu installation went on fine, and most of the hardware are working. An important point to note is that the wireless networking adaptor didn’t work while booting using the ubuntu 9.04 live cd, but worked fine when running from harddisk. Also the spdif out didn’t give any thing unless the surround volume in alsa is up and unmuted. Also auto matic front muting doesn’t work when the headphone is plugged to the spdif/headphone out.

I have not yet tested the fingerprint, and currently working on getting the FN+Up and FN+Down to increase and decrease the volume. Will post the progress as things go on

After about a years construction and refurbishment work finally got my workshop to a  ‘almost complete’ stage. The only problem now is from the huge amount of dust and the rats. Got to find a workaround for those 2 problems as well.

Here are the pics.

Check this out..

http://www.hobbytechlk.net

It is a knowledge sharing websites for hobbyists interested in Electronics, Robotics, Remote Controlled Cars, Airplanes, Trains, and Robot building.

Recently while configuring a courier-imap I came across a frustrating error where I couldnot login using the correct username and password. I was using authpam module and the server logs just stated Login Failed, and then Logout.

Enabling debug level 2 didn’t help much, but then figured out that I had set DEFDOMAIN in the imapd config file which failed the pam authentication.

Also I found out that each change to authdaemonrc takes effect only after I restart courier-authdaemon and not courier-imap or courier-imap-ssl.

Recently I came across a situation where I needed to convert a .vmdk (VMware 6) disk image to a .vdi (VirtualBox) image.

I tried the method in http://thedarkmaster.wordpress.com/2007/03/12/vmware-virtual-machine-to-virtual-box-conversion-how-to/ but it didn’t seem to work for me. The vdi image was not bootable. The VirtualBox VM gave a fatal error saying that no bootable media were found.

The following is another workaround which needs only a linux installation / live cd and VirtualBox.

1. Create a new VirtualMachine in VirtualBox, and use an existing linux vdi image or put in a live linux cd in to your physical cdrom drive and set the VM to use the physical cdrom drive.
2. Create a “New” dynamically expanding vdi image (Use the File->Virtual Disk Manager in Virual Box to do this).
3. In your virtual machine add this newly created image as a hard disk drive. (primary slave)
4. Go back to the Virtual Disk Manager and “Add” a new disk image, select your vmdk image as the image file.
5. Add this image to your VM as a hard disk drive (secondary slave).
6. Boot the VM
7. Open a terminal and try to mount the secondary slave. In my case it was /dev/sdc2. If it mounts without any errors you are good to proceed.

#mkdir /mnt/disk

#mount -t ntfs /dev/sdc2 /mnt/disk

8. Dump the secondary slave to the primary slave using dd

# dd if=/dev/sdc of=/dev/sdb

This would take some time (for me it took around an hour to dump a 9GB image)

9. Turn off the VM.
10. Remove all the hard disk drives from the VM leaving only the newly created vdi (mounted as primary slave)
11. Make it the primary master
12. Boot the VM
13. If every thing went ok then the vm should boot fine with the new vdi image, and would be identical to the vmware virtual machine using the vmdk image.

Note

If your vdi image has a Windows OS then you would need to take a look at http://www.virtualbox.org/wiki/Migrate_Windows.

Further you may need to enable IO-APIC in the virtual image.

Recently I bought three stepper motors from a junk seller in ‘armour street’. It costed me Rs. 300 each. The labels on these motors were almost unreadable, but since I selected all three motors of the same type I was able to put the remaining contents of the labels to find out about the motors.

The labels stated the following.

5-PHASE STEPPING MOTOR
A5729-9115FV
DC 2.0A 0.347 OHMS / PHASE
0.72 * / STEP
FC6-0435 02
ORIENTAL MOTOR CO LTD

Each motor has 5 wires coming out, and by disassembling one motor I found it was wound in a penta wiring (All coils are connected end to end to form a pentagon).

The next job was to get the motor to spin. I searched the web for an appropriate controller but couldn’t find any that satisfied my need. So I decided to build my own.

I found the energizing sequence here.

I thought of using a PIC16F84 (since I had experimented with this chip and had one in my parts box) as the controller and five IRF540 s and five IRF9540 s as the driver MOSFETs.

I wrote the following code in C in order to spin the motor in a single direction. (My intension was to some how get this motor working)

#define __16f84

#include"pic/pic16f84.h"// Set the __CONFIG word:

typedef unsigned int word;

word at 0x2007  __CONFIG = 0x3ffa;

const unsigned int excitations[] = {22,18,26,10,11,9,13,5,21,20};

signed char excitation_index = 0;

 void forward(void){

 // increment the index;

 excitation_index++;

 PORTB = excitations[excitation_index%10];

}

void main(void) {

 TRISA = 0x00;

 TRISB = 0x00;

 PORTA = 0x00;

 PORTB = 0x00;

 T0CS = 0;

 T0IE = 0;

 GIE = 0;

 PSA = 0;

 PS0 = 1;

 PS1 = 1;

 PS2 = 1;

 T0IE = 1;

 GIE = 1;

 while(1){

 	// increment port a to indicate that the chip is doing it's job.

 	PORTA = PORTA + 1;

 }

}

void intr_handler(void) interrupt {

 T0IF = 0;

 GIE = 0;

 forward();

 GIE = 0;

}

I used the SDCC compiler for GNU/Linux to compile and used PIKDEV to burn the hex file to the chip. PIKDEV failed to verify the chip after burining the hex, so I switched to Windows and used ICProg to burn the chip which was successful.

The following is the basic driver schematic I used to run the motor.

The Port B’s B0-B5 are connected to 1-5 in the diagram respectively. The motor connects to A,B,C,D,E points in the schematic.

I setup my proto board and powered it up with a 300mA power supply. It didnt work as expected. The motor kept vibrating without turning. After hours of checking what was wrong I figured out that the power was not enough to drive the motor.

Then I used a 1000mA 12V power supply to power the motor and the 300mA 12V to power the uC board.

The motor started to spin with very low torque and very low speed. Also about 2 of the IRF540N s were getting hotter than the others. The investigation is pending.

I think thats because there is no PWM used in this driver. Planing to add a PWM to this driver as the next modification.

By the way I destroyed 2 PIC’s in the process, one by applying 12Volts to PORTB and another by burning the hex file on to it too many times. ( I had used it for about more than a year and I suppose it went out of the maximum number of times it could be reprogrammed ). Any way I finally got the 5-phase to run.

See it working in the following video. Sorry about the very bad quality.

I just checked out a PHP project (SAHANA), opened it in eclipse PDT, and found out that the code navigation is not working. I couldnt view a function’s code by just ctrl+click ing on the function call.

Asked Ravindra and this is the solution he gave me.

What I did was just created a new dummy PHP project named test in eclipse,

got the .project file which was generated in the project folder (test) and copied it over the .project file I had in the project (sahana).

Opened up the newly copied .project (in sahana) and edited the <name></name> to match the name of the project (say sahana-phase 2).

Closed and re-opened eclipse.

BINGO!!! now I have code navigation.

Spring RCP Tutorial 1 – The Basics.

Note : First of all I have to tell you that what I write here is what I experienced while learning Spring RCP. I am no expert in Spring RCP and there may be mistakes and wrong do’s in this tutorial. Experts are welcome to point them out.

Introduction.

Spring RCP is a platform that can be used to develop high quality swing applications in a very short time. Since this technology is relatively new the number of tutorials about it is very small. Therefore I have decided to write my own.

Getting Started.

You will need too download the Spring RCP 0.2.1 from http://spring-rich-c.sourceforge.net/

Start a new Project in NetBeans.

1. Open up Netbeans.
2. Select File à New Project
3. Enter SpringRCP-1 as the project name and select an appropriate project location.

Setting up the libraries.

1. On Netbeans select Tools à Library Manager.
2. Click New Library and type in the name SpringRCP_0.2.1, select library type as Class Library.
3. Click Add Jar/ Folder and browse to the spring-richclient-full-0.2.1.jar file in the downloaded SpringRCP distribution. (spring-richclient-0.2.1\full\spring-richclient-full-0.2.1.jar).
4. Also add the following libraries. These can be found in the Spring RCP distribution under spring-richclient-0.2.1\lib. (version and release numbers were ommited from file names to reduce confusion)
   • log4j.jar
   • spring-beans.jar
   • spring-core.jar
   • spring-context.jar
   • commons-logging.jar
   • looks.jar
5. Click OK.
6. Right Click on the project node on the Projects Tab and select properties.

   

7. Select Libraries : Add Library and add the SpringRCP_0.2.1 library which we created before to the project.

Writing the Hello World Application

First we need to create an application context xml file which will hold all bean definitions of the application.

I choose to create the application-context.xml file under src/resources/ directory of the project direcotry structure.

Create a new xml file named application-context.xml in the above folder. ( you will have to create the resources folder under the src folder first)

The content of the applicatoin-context.xml is as follows.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" 

"http://www.springframework.org/dtd/spring-beans.dtd">

 <beans>

    <bean name="application" class="org.springframework.richclient.application.Application">

        <constructor-arg>

            <ref bean="applicationLifecycleAdvisor" />

        </constructor-arg>

    </bean>

    <bean name="applicationLifecycleAdvisor" class="springrcp.tutorial1.HelloWorldLifecycleAdvisor">

        <property name="startingPageId">

            <value>helloWorldPage</value>

        </property>

    </bean>

    <bean name="helloWorldPage" class="org.springframework.richclient.application.support.DefaultViewDescriptor">

        <property name="viewClass">

            <value>springrcp.tutorial1.HelloWorldView</value>

        </property>

    </bean>

    <bean id="serviceLocator" class="org.springframework.richclient.application.ApplicationServicesLocator">

        <property name="applicationServices" ref="applicationServices"/>

    </bean>

    <bean id="applicationServices" class="org.springframework.richclient.application.support.DefaultApplicationServices">

        <property name="imageSourceId"><idref bean="imageSource"/></property>

    </bean>

    <bean id="imageSource" class="org.springframework.richclient.image.DefaultImageSource">

        <constructor-arg>

            <ref bean="imageResourcesFactory"/>

        </constructor-arg>

    </bean>

    <bean id="imageResourcesFactory" class="org.springframework.context.support.ResourceMapFactoryBean">

        <property name="location">

            <value>resources/images.properties</value>

        </property>

        <property name="resourceBasePath">

            <value>resources/images/</value>

        </property>

    </bean>

</beans>

If you are familiar with the spring framwork and AOP (don’t worry if you are not) you will notice that every thing is done through dependency injection.

I will explain each and every bean definition separately which comes the <beans> element.

<bean name="application" class="org.springframework.richclient.application.Application">

        <constructor-arg>

            <ref bean="applicationLifecycleAdvisor" />

        </constructor-arg>

</bean> 

This bean is the main bean which defines the actual application. It must be given the name application. (For the time being remember that as a rule. You will know why it is given that name later.)

If you take a look at the java doc of the class org.springframework.richclient.application.Application you will see that there are two constructors one which accepts two arguments and another with a single argument. For the moment forget about the constructor with two arguments. We’ll use it in a later tutorial.

The constructor with a single argument accepts a org.springframework.richclient.application.config.ApplicationLifecycleAdvisor.

An application lifecycle advisor is class which contains methods that will be called at different stateges of the applicatoin such as onStartup, onClose etc. (This concept is called callbacks, If you want to know more just read some articles on Aspect Oriented Programming (AOP))

<bean name="applicationLifecycleAdvisor" class="springrcp.tutorial1.HelloWorldLifecycleAdvisor">

    <property name="startingPageId">

            <value>helloWorldPage</value>

    </property>

</bean>

Since the class ApplicationLifecyclceAdvisor is abstract I’ll have to write my own life cycle advisor inheriting the above. I’ll name that class HelloworldLifecycelAdvisor.

The ApplicationLifecycelAdvisor class specifies what page / user interface should be shown when the application is started. This is specified through the property “startingPageId”. I have specified the value as helloWorldPage where it is a view descriptor bean.

HelloWorldLifecycleAdvisor.java is as follows.

package springrcp.tutorial1;

import org.springframework.richclient.application.config.ApplicationLifecycleAdvisor;

/**

 *

 * @author Ravith

 */

public class HelloWorldLifecycleAdvisor extends ApplicationLifecycleAdvisor{

    /**

     * Creates a new instance of HelloWorldLifecycleAdvisor

     */

    public HelloWorldLifecycleAdvisor() {

    }     

}

Let us now see what a view descriptor is. As the name implies it tells what are the things that make up the view / user interface.

<bean name="helloWorldPage" class="org.springframework.richclient.application.support.DefaultViewDescriptor">

    <property name="viewClass">

        <value>springrcp.tutorial1.HelloWorldView</value>

    </property>

</bean>

The HelloWorldView.java is as follows.

package springrcp.tutorial1;

import java.awt.BorderLayout;

import javax.swing.JComponent;

import javax.swing.JLabel;

import org.springframework.richclient.application.support.AbstractView;

/**

 *

 * @author Ravith

 */

public class HelloWorldView extends AbstractView{    

    /** Creates a new instance of HelloWorldView */

    public HelloWorldView() {

    }

    protected JComponent createControl() {

       JLabel lblHelloWorld = new JLabel();//create a new label

       lblHelloWorld.setText("Hello Spring RCP World !"); // set the text

       return lblHelloWorld; // return the label. 

    }        

}

The HelloWorldView class is a subclass of AbstractView which inturn implements the org.springframework.richclient.application.View interface. We need to override the createControl() method to return our user interface. In the above code I have overridden the method to return a simple text lable with the text “Hello Spring RCP World !”.

Now let us take a look at the remaining bean definitions.

<bean id=”serviceLocator” class=”org.springframework.richclient.application.ApplicationServicesLocator”> <property name=”applicationServices” ref=”applicationServices”/>

</bean>

This bean is responsible for locating the application services which actually do the business logic of the application. Just remember it as it is. We’ll use it in more detail when we are familiar with things.

I will use the default set of application services because we need to configure a image source for our application. (I’ve tried without this and it fails with an error.)

<bean id=”applicationServices” class=”org.springframework.richclient.application.support.DefaultApplicationServices”>

<property name=”imageSourceId”><idref bean=”imageSource”/></property>

</bean>

The bean imageSource will be responsible for mapping image keys to actual images. Don’t worry abt this right now. U’ll understand it in a minute.

<bean id=”imageSource” class=”org.springframework.richclient.image.DefaultImageSource”>

<constructor-arg>

<ref bean=”imageResourcesFactory”/>

</constructor-arg>

</bean>

<bean id=”imageResourcesFactory” class=”org.springframework.context.support.ResourceMapFactoryBean”>

<property name=”location”>

<value>resources/images.properties</value>

</property>

<property name=”resourceBasePath”>

<value>resources/images/</value>

</property>

</bean>

The imageResourcesFactory class is used to load a map of keys and image file names from a resource bundle properties file, in this case named images.properties.

The images.properties file is a simple text file with the extention .properties and contains the following line of text.

applicationInfo.image=image1.gif

The resourceBasePath property of the imageResourceFactory bean is used to append any common path used by all images of our application.

So .. that means…. You guessed it right.!!

“image1.gif” will be taken as “resources/images/image1.gif”

This is how the file structure of the application looks like now.

So the remaining job is to create a class that will contain the main method to execute our hello world application.

The Main.java will be as follows.

package springrcp.tutorial1;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import org.springframework.richclient.application.ApplicationLauncher;

/**

*

* @author Ravith

*/

public class Main {

/** Creates a new instance of Main */

public Main() {

}

public static void main(String[] args){

String appContextPath = “resources/application-context.xml”;

ApplicationContext appCtx = new ClassPathXmlApplicationContext(appContextPath);

new ApplicationLauncher(appCtx);

}

}

We need to tell the spring framework to use our application-context.xml file to configure the beans and perform the IOC and AOP functionalities. (Read some spring tutorials if you really want to understand how IOC and AOP works).

The ClassPathXmlApplicationContext is created by passing the path of the xml configuration file. This ApplicationContext is then passed in to the ApplicationLauncher which will launch the application.

I hope I didn’t leave you more confused than you started. Any way if there are parts of this tutorial that need to be explained more please drop in a comment. Also point any mistakes if there are any.

In the next tutorial we will take a look at splash screens and a little advanced scenario.

Until then you are free to mess up with this example.

While working on my degree project i came across a situation where i needed a one-to-one relationship. Among the two methods to implement such relationship in hibernate, i choose to use the foreign-key method other than the shared primary key method.

I was unable to do a schemaExport because of xdoclet generating two unique=”true” attributes in the .hbm file.

Google found me this link http://opensource.atlassian.com/projects/xdoclet/browse/XDT-1665 where it is reported as a bug which is open at the time of writing.

After playing around with it for some time i figured out that by adding a @hibernate.column would stop Xdoclet generating two unique=”true” attributes which in turn is converted to the mapping xml file which becomes invalid according to the hibernate-3.0.dtd.

Initial xdoclet tag was.

@hibernate.many-to-one
class=”someClass”
unique=”true”

I was able to get rid of this error by adding a column and setting the unique-key.
@hibernate.many-to-one
class=”someClass”
unique=”true”
foreign-key=”myFK”
@hibernate.column
name=”fkColumn”
unique-key=”myFK”