[英]JAVA read write com port
I have an Arduino which sends me the string ping , and as you can see in my code, when I read ping , I write pong 我有一个Arduino,向我发送字符串ping ,正如您在代码中看到的那样,当我阅读ping时 ,我会写pong
It's like a watchdog. 就像看门狗一样。 But the line: output.write("pong".getBytes());
但是这一行:output.write(“ pong” .getBytes()); is not working well.
运作不正常。 I do can read, but cannot write.
我可以阅读,但是不能写。
Anyone can help me please? 有人可以帮我吗?
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/tty.usbserial-A9007UX1", // Mac OS X
"/dev/ttyACM0", // Raspberry Pi
"/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 = 115200;
public void initialize() {
// the next line is for Raspberry Pi and
// gets us into the while loop and was suggested here was suggested http://www.raspberrypi.org/phpBB3/viewtopic.php?f=81&t=32186
// System.setProperty("gnu.io.rxtx.SerialPorts", "/dev/ttyACM0");
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);
if(inputLine.equals("ping")){
System.out.println("pong");
output.write("pong".getBytes());
}
else{
System.out.println("no");
}
} 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");
}
}
Based on the fact that you are using readLine
to read the "ping"
I am going to guess and say that you also have to write a newline character at the end of your "pong"
. 基于您正在使用
readLine
读取"ping"
这一事实,我将猜测并说您还必须在"pong"
的末尾写一个换行符。 You may also need to flush the output stream if it is a buffered stream. 如果输出流是缓冲流,则可能还需要刷新它。
So, 所以,
output.write("pong\n".getBytes());
output.flush(); // this line might be unnecessary, but try it and see
But the line: output.write("pong".getBytes());
但是这一行:output.write(“ pong” .getBytes()); is not working well.
运作不正常。
More precisely, please. 更准确地说,请。
What if you turn your test around: Whenever your java sends something to Arduino, arduino returns it and java shows what is received in the SerialEvent callback 如果您不进行测试,该怎么办:每当Java向Arduino发送东西时,arduino都会将其返回,并且Java会显示SerialEvent回调中收到的内容
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