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reading serial ports using Java

807580Sep 2 2010 — edited Sep 3 2010
hi !
I am interfacing microcontoller to my pc and I am looking for a simple java code that will do the following :

1- send a flag char say '^' on serial port and wait for response with a '^' from micro.
2- if response found then go ahead and read the serial buffer (preferably circular )
3- do something here
4- go back to step 1.

I found online code called SimpleRead.java , it does read the incoming data but is acting strange by printing the same data multiple times, putting extra spaces between charaters etc.
import java.io.*;
import java.util.*;
import javax.comm.*;

public class SimpleRead implements Runnable, SerialPortEventListener {
    static CommPortIdentifier portId;
    static Enumeration portList;

    InputStream inputStream;
    SerialPort serialPort;
    Thread readThread;

    public static void main(String[] args) {
        portList = CommPortIdentifier.getPortIdentifiers();

        while (portList.hasMoreElements()) {
            portId = (CommPortIdentifier) portList.nextElement();
            if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
                 if (portId.getName().equals("COM1")) {
			//                if (portId.getName().equals("/dev/term/a")) {
                    SimpleRead reader = new SimpleRead();
                }
            }
        }
    }

    public SimpleRead() {
        try {
            serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);
        } catch (PortInUseException e) {System.out.println(e);}
        try {
            inputStream = serialPort.getInputStream();
        } catch (IOException e) {System.out.println(e);}
	try {
            serialPort.addEventListener(this);
	} catch (TooManyListenersException e) {System.out.println(e);}
        serialPort.notifyOnDataAvailable(true);
        try {
            serialPort.setSerialPortParams(9600,
                SerialPort.DATABITS_8,
                SerialPort.STOPBITS_1,
                SerialPort.PARITY_NONE);
        } catch (UnsupportedCommOperationException e) {System.out.println(e);}
        readThread = new Thread(this);
        readThread.start();
    }

    public void run() {
        try {
            Thread.sleep(20000);
        } catch (InterruptedException e) {System.out.println(e);}
    }

    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[200];

            try {
                while (inputStream.available() > 0) {
                    int numBytes = inputStream.read(readBuffer);
                }
                System.out.print(new String(readBuffer));
            } catch (IOException e) {System.out.println(e);}
            break;
        }
    }
}
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Post Details
Locked on Oct 1 2010
Added on Sep 2 2010
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