Tutorial - Communication through serial port in a java application running Beagleboard with Angstrom OS - RxTx library is needed.

1. ###############################################################
## CETENE/LINCS - CampinaGrande/Recife - Paraíba/Pernambuco - Brasil ##
## Dalton Cézane Gomes Valadares – Embedded Systems Developer ##
## Master's/Specialist/Bachelor in Computer Science-UFCG ##
###############################################################
How to communicate Java application via serial port on Beagleboard running
Angstrom
-Install Java on Angstrom
opkg install openjdk-6-jre
-Install RxTx Library for serial communication
opkg install librxtx-java librxtx-jni
-Create a class to open a serial connection and communicate with it:
package cetene.lincs.cg.bioquali;
import gnu.io.CommPortIdentifier;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import gnu.io.UnsupportedCommOperationException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.TooManyListenersException;
/**
* @author …
*/
public class SerialComm implements SerialPortEventListener {
private static final String EMBEDDED_LINUX_PORT = "/dev/ttyS2";
private static final String WINDOWS_PORT = "COM1";
InputStream inputStream;
public void execute() {
String portName = getPortNameByOS();
CommPortIdentifier portId = getPortIdentifier(portName);
if(portId != null) {
try {
SerialPort serialPort = (SerialPort)
portId.open(this.getClass().getName(), 2000);
inputStream = serialPort.getInputStream();
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);

2. serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
}
catch (PortInUseException e) {}
catch (IOException e) {}
catch (UnsupportedCommOperationException e) {
e.printStackTrace();
}
catch (TooManyListenersException e) {}
} else {
System.out.println("Porta Serial não disponível");
}
}
/**
* Get The port name
**/
private String getPortNameByOS() {
String osname = System.getProperty("os.name","").toLowerCase();
if ( osname.startsWith("windows") ) {
// windows
return WINDOWS_PORT;
} else if (osname.startsWith("linux")) {
// linux
return EMBEDDED_LINUX_PORT; //Angstrom running on
Beagleboard...
} else if ( osname.startsWith("mac") ) {
// mac
return "???";
} else {
System.out.println("Sorry, your operating system is not supported");
System.exit(1);
return null;
}
}
/**
*Get the Port Identifier
**/
private CommPortIdentifier getPortIdentifier(String portName) {
Enumeration portList = CommPortIdentifier.getPortIdentifiers();
Boolean portFound = false;
while (portList.hasMoreElements()) {
CommPortIdentifier portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {

3. System.out.println("Available port: " + portId.getName());
if (portId.getName().equals(portName)) {
System.out.println("Found port: "+portName);
portFound = true;
return portId;
}
}
}
return null;
}
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 {
int numBytes = 0;
int count = 0;
while (inputStream.available() > 0 && count <
5) {
numBytes =
inputStream.read(readBuffer);
count++;
}
String result = new String(readBuffer);
result += result.substring(1, numBytes);
System.out.println(result);
// System.out.println(readBuffer);
} catch (IOException e) {}
break;
}
}
}
-After compile, run the application as follow:
java -cp .:/usr/share/java/RXTXcomm.jar

4. -Djava.library.path=/lib:/usr/lib/jni
-Dgnu.io.rxtx.SerialPorts=/dev/ttyACM0 SerialComm
/dev/ttyACM0
-In my case, adding other libs:
java -cp ./EmbeddedBioquali/bin/.:./EmbeddedBioquali/lib/fluent-hc-
4.2.2.jar:./EmbeddedBioquali/lib/httpcore-
4.2.2.jar:./EmbeddedBioquali/lib/commons-codec-
1.6.jar:./EmbeddedBioquali/lib/httpclient-
4.2.2.jar:./EmbeddedBioquali/lib/httpmime-
4.2.2.jar:./EmbeddedBioquali/lib/commons-logging-
1.1.1.jar:./EmbeddedBioquali/lib/httpclient-cache-
4.2.2.jar:/usr/share/java/RXTXcomm.jar -Djava.library.path=/lib:/usr/lib/jni
-Dgnu.io.rxtx.SerialPorts=/dev/ttyS2 TestService /dev/ttyS2
Reference:
http://embeddedgeeks.wordpress.com/2012/02/26/arduino-beagleboard-serial-
communication-using-java-rxtx/