Colony

DEV-NOTES - Development notes for the cal_sta_server Java code

Author: John Sexton

Date: 3/20/11

SUMMARY:

-Tried to install Sun's Java Comm API, doesn't work for 64-bit machines.

-Changed from open source IcedTea Java 6 to Sun's Java 6.

-Tried to install RXTX library. Need special version for 64-bit. Does not

   allow you to open any port, only can open what it scans.

-Downloaded RXTX source code, added "arduino" and "robot" port prefixes

   to RXTX library, compiled it and installed it on Marvin.

USEFUL JAVA LOCATIONS:

/usr/lib/jvm -

   location of java installations

/usr/lib/jvm/java-6-sun/jre/lib/ext -

   java extension .jar files (like RXTXcomm.jar) go here (for Sun's Java)

/usr/lib/jvm/java-6-sun/jre/lib/amd64 -

   the librxtx______.so files go here (for Sun's Java + 64-bit)

   /usr/lib/jvm/java-6-sun/jre/lib/amd64

                     ^               ^

                Sun's Java       64-bit architecture

USEFUL WEBSITES:

http://en.wikibooks.org/wiki/Serial_Programming/Serial_Java -

   General overview of serial programming in Java.

http://download.oracle.com/docs/cd/E17802_01/products/products/javacomm/reference/api/index.html -

   API for javax.comm / gnu.io

http://www.capybara.org/~dfraser/archives/29 -

   Article describing how to edit RXTX source code to add port prefixes.

http://rxtx.qbang.org/wiki/index.php/Main_Page -

   RXTX development wiki. Very good resource for installing and obtaining

   source code.

http://www.cloudhopper.com/opensource/rxtx/ -

   Location of 64-bit compiled binaries for RXTX library.

NOTES:

Java does not play nice with serial ports right out of the box. You must

install additional libraries to gain the ability to speak to serial ports

in Java. The most common library that I found is the JAVA COMMUNICATIONS

API LIBRARY.

== Sun's Java Communications API ==

Sun does a very poor job of maintaining this library (after all, they

support platform-independent development and this is difficult when a

serial port inherently relies on the underlying hardware). My first

attempts to successfully listen over a serial port involved using Sun's

implementation of the Java Communications API. It was difficult to find a

good download of this online, but I eventually ended up using an Oracle

website (http://www.oracle.com/technetwork/java/index-jsp-141752.html) to

obtain the library. Followed installation instructions and successfully

installed, but when I tried to run a program I got an error which cited

the ELF compiled binary file. Also mentioned the word size might be wrong.

This error was confirmed online where I found support for the fact that

Sun/Oracle only supports 32-bit versions of the Java Communications API

and doesn't support windows. All of these limitations led me to abandon

using Sun's version.

== RXTX Library ==

I found an open source library called the RXTX library which follows the

Java Communications API exactly (except it's called 'gnu.io' instead of

'javax.comm'). The development website

(http://rxtx.qbang.org/wiki/index.php/Main_Page) was very useful. I was

able to successfully install the RXTX library, but when I tried to run

sample code, Java seg-faulted (OMG... XD). In an attempt to fix this, I

removed the open source IcedTea java and installed Sun's Java, but the

error still remained. I then traced the error back to the Thread function,

so I believe the problem is not actualy with the RXTX functionality that

we need and instead has to do with using threads with the RXTX library.

I proceeded to write a small Java program to test the

RXTX library, and discovered that you can only address ports which the

library finds on its own. This was a problem because the library only

looked for a few prefixes and did not show the 'arduino' or the 'robot#'

nodes in the /dev folder. I found an article online

(http://www.capybara.org/~dfraser/archives/29) which describes how

to edit the source code for the RXTX library to include more ports. I

used the link included in the article to obtain the source code, but when

I edited the necessary source file (RXTXCommDriver.java), recompiled it

into a .jar file again (had to remove a 'import javax.comm.*' line from

the source file which seemed strange to me), and transfered it into the

proper directory (/usr/lib/jvm/java-6-sun/jre/lib/ext) it did not work.

Java threw an error which I can't remember the content of at the moment

(but it wasn't a seg-fault like the thread error). To obtain a better copy

of the source code, I again resorted to the RXTX development wiki

(http://rxtx.qbang.org/wiki/index.php/Main_Page). I downloaded a recent

copy of the source code, unzipped it, ran '/configure', and ran 'make'.

I received some errors, but there was still a brand new 'RXTXComm.jar'

file in the folder now, so I proceeded to install it

(replace the RXTXComm.jar file in the

/usr/lib/jvm/java-6-sun/jre/lib/ext folder). To my relief, my test program

did NOT throw an error this time. I did get a warning that looked like this:

WARNING:  RXTX Version mismatch

        Jar version = RXTX-2.2

        native lib Version = RXTX-2.2pre2 

(versions are not the same as the versions I saw, but I did have a mismatch

warning). To solve this, I just went back to the development wiki and

found the version that made these two lines agree (turned out to be 

rxtx-2.2pre2). Now (finally), my little test program can find the 'arduino'

and 'robot#' ports and listen to them!

Hope this helps for anyone who has to take this project up after me!

import gnu.io.*;

public class SimpleRead {

	static CommPortIdentifier portId;

    static Enumeration	      portList;

    InputStream		      inputStream;

    SerialPort		      serialPort;

    Thread		      readThread;

    public static void main(String[] args) {

    boolean		      portFound = false;

    String		      defaultPort = "/dev/ttyUSB0";

 	if (args.length > 0) {

	    defaultPort = args[0];

	} 

	portList = CommPortIdentifier.getPortIdentifiers();

	while (portList.hasMoreElements()) {

	    portId = (CommPortIdentifier) portList.nextElement();

	    if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {

		if (portId.getName().equals(defaultPort)) {

		    System.out.println("Found port: "+defaultPort);

		    portFound = true;

		    SimpleRead reader = new SimpleRead();

		} 

	    } 

	} 

	if (!portFound) {

	    System.out.println("port " + defaultPort + " not found.");

	} 

    Opens

    } 

    /**

     * Constructor declaration

     *

     *

     * @see

     */

    public SimpleRead() {

	try {

	    serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);

	} catch (PortInUseException e) {}

	try {

	    inputStream = serialPort.getInputStream();

	} catch (IOException e) {}

	try {

	    serialPort.addEventListener(this);

	} catch (TooManyListenersException e) {}

	serialPort.notifyOnDataAvailable(true);

	try {

	    serialPort.setSerialPortParams(9600, SerialPort.DATABITS_8, 

					   SerialPort.STOPBITS_1, 

					   SerialPort.PARITY_NONE);

	} catch (UnsupportedCommOperationException e) {}

	readThread = new Thread(this);

	readThread.start();

    }

    /**

     * Method declaration

     *

     *

     * @see

     */

    public void run() {

	try {

	    Thread.sleep(20000);

	} catch (InterruptedException e) {}

    } 

    /**

     * Method declaration

     *

     *

     * @param event

     *

     * @see

     */

    public void serialEvent(SerialPortEvent event) {

	switch (event.getEventType()) {

	case SerialPortEvent.BI:

	case SerialPortEvent.OE:

	case SerialPortEvent.FE:

	case SerialPortEvent.PE:

	case SerialPortEvent.CD:

	case SerialPortEvent.CTS:

	case SerialPortEvent.DSR:

	case SerialPortEvent.RI:

	case SerialPortEvent.OUTPUT_BUFFER_EMPTY:

	    break;

	case SerialPortEvent.DATA_AVAILABLE:

	    byte[] readBuffer = new byte[20];

	    try {

		while (inputStream.available() > 0) {

		    int numBytes = inputStream.read(readBuffer);

		} 

		System.out.print(new String(readBuffer));

	    } catch (IOException e) {}

	    break;

	}

    } 

}

import java.io.*;

import java.util.Enumeration;

import gnu.io.*;

import java.lang.Character;

public class SimpleSerial {

	public static void main(String[] args) {

		String port_path = "/dev/ttyUSB0";

/*

		FileInputStream port_stream;

		try {

			port_stream = new FileInputStream(port_path);

		} catch (IOException e) {

			System.out.print(e);

		}

		port_stream.getFD()

*/

		Enumeration ports = CommPortIdentifier.getPortIdentifiers();

		CommPortIdentifier port = null, arduino = null;

		SerialPort ser = null;

		InputStream inSt = null;

		while (ports.hasMoreElements()) {

			port = (CommPortIdentifier)ports.nextElement();

			System.out.println(port.getName());

			if (port.getName().equals("/dev/arduino")) {

				arduino = port;

			}

		}

		System.out.println(arduino.getName());

		try{

			ser = (SerialPort) arduino.open("cal_sta_server", 2000);

		} catch (PortInUseException e) {System.out.print(e);}

		try {

		    inSt = ser.getInputStream();

		} catch (IOException e) {System.out.print(e);}

		try {

		    ser.setSerialPortParams(19200, SerialPort.DATABITS_8, 

						   SerialPort.STOPBITS_1, 

						   SerialPort.PARITY_NONE);

		} catch (UnsupportedCommOperationException e) {}

		while (true) {

			try {

				if (inSt.available() > 0) {

					System.out.print((char)inSt.read());

				}

			} catch (IOException e) {System.out.print(e);}

		}

	}

}