Sunday, June 23, 2013

Create Java project using librxtx-java in Netbeans, work with Arduino

remark: This example work on Ubuntu.

Before create our Java project using librxtx-java, we have to setup something in our PC, refer to lastr post "Setup RxTx for Arduino and Java example".

Create Netbeans Java Project:

- Start Netbeans, Click File -> New Project..., to create a project of Java Application in Java categories.


- with Project Name of SerialTest


Modify the code:

Basically, it's same as the example code in Arduino Playground of Arduino and Java, except the package, and PORT_NAMES of "/dev/ttyACM0".

package serialtest;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import gnu.io.CommPortIdentifier; 
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent; 
import gnu.io.SerialPortEventListener; 
import java.util.Enumeration;


public class SerialTest implements SerialPortEventListener {
 SerialPort serialPort;
        /** The port we're normally going to use. */
 private static final String PORT_NAMES[] = { 
                        "/dev/ttyACM0", //for Ubuntu
   "/dev/tty.usbserial-A9007UX1", // Mac OS X
   "/dev/ttyUSB0", // Linux
   "COM3", // Windows
 };
 /**
 * A BufferedReader which will be fed by a InputStreamReader 
 * converting the bytes into characters 
 * making the displayed results codepage independent
 */
 private BufferedReader input;
 /** The output stream to the port */
 private OutputStream output;
 /** Milliseconds to block while waiting for port open */
 private static final int TIME_OUT = 2000;
 /** Default bits per second for COM port. */
 private static final int DATA_RATE = 9600;

 public void initialize() {
  CommPortIdentifier portId = null;
  Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

  //First, Find an instance of serial port as set in PORT_NAMES.
  while (portEnum.hasMoreElements()) {
   CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
   for (String portName : PORT_NAMES) {
    if (currPortId.getName().equals(portName)) {
     portId = currPortId;
     break;
    }
   }
  }
  if (portId == null) {
   System.out.println("Could not find COM port.");
   return;
  }

  try {
   // open serial port, and use class name for the appName.
   serialPort = (SerialPort) portId.open(this.getClass().getName(),
     TIME_OUT);

   // set port parameters
   serialPort.setSerialPortParams(DATA_RATE,
     SerialPort.DATABITS_8,
     SerialPort.STOPBITS_1,
     SerialPort.PARITY_NONE);

   // open the streams
   input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
   output = serialPort.getOutputStream();

   // add event listeners
   serialPort.addEventListener(this);
   serialPort.notifyOnDataAvailable(true);
  } catch (Exception e) {
   System.err.println(e.toString());
  }
 }

 /**
  * This should be called when you stop using the port.
  * This will prevent port locking on platforms like Linux.
  */
 public synchronized void close() {
  if (serialPort != null) {
   serialPort.removeEventListener();
   serialPort.close();
  }
 }

 /**
  * Handle an event on the serial port. Read the data and print it.
  */
 public synchronized void serialEvent(SerialPortEvent oEvent) {
  if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
   try {
    String inputLine=input.readLine();
    System.out.println(inputLine);
   } catch (Exception e) {
    System.err.println(e.toString());
   }
  }
  // Ignore all the other eventTypes, but you should consider the other ones.
 }

 public static void main(String[] args) throws Exception {
  SerialTest main = new SerialTest();
  main.initialize();
  Thread t=new Thread() {
   public void run() {
    //the following line will keep this app alive for 1000 seconds,
    //waiting for events to occur and responding to them (printing incoming messages to console).
    try {Thread.sleep(1000000);} catch (InterruptedException ie) {}
   }
  };
  t.start();
  System.out.println("Started");
 }
}

In order to access Serial port in Ubuntu, you have to setup the right of the port. Refer to the post Fixed the problem of "No device found on COM1" for /dev/ttyACM0. You have to enter the following command before run the code:

$sudo chmod a+rw /dev/ttyACM0

If everything OK, you can run the program as shown below, the message "Hello world" will be printed every second in Output windows.



Next:
- Communication between Arduino and PC running Java, with JavaFX UI

2 comments:

  1. Sorry,
    I'm try this code, but output is "Could not find COM port."
    what should i do?

    ReplyDelete
  2. How can I use the UART ports raspberry?

    This is the port:
    /dev/ttyAMA0

    ReplyDelete