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[英]Using the serial port ttyUSB0 in Android with Digi Xbee Java Api
[英]Merge XBee api fragments from serial port
我尝试通过RS-232串行端口以API模式合并Xbee(802.15.4)收到的数据包的片段。 我从java的jssc库中使用readBytes方法获取片段。
这是我的接收代码
private static class PortReader implements SerialPortEventListener {
@Override
public void serialEvent(SerialPortEvent event) {
if(event.isRXCHAR() && event.getEventValue() > 0) {
try {
byte[] receivedData = serialPort.readBytes(event.getEventValue());
if(Utils.isConfirmPacket(Utils.toHex(receivedData))){
System.out.println("XBee confim that msg is sent!");
}else{
System.out.println("Received response from port: " + Utils.toHex(receivedData));
int dataLength = Utils.toHex(receivedData).length();
receiveFile("testRx", receivedData, dataLength);
}
}
catch (SerialPortException ex) {
System.out.println("Error in receiving response from port: " + ex);
}
}
}
我的receiveFile()方法需要在一个片段中完整的数据包。 这是我在控制台中得到的:
Received response from port: 7e003c8100013200
Received response from port: 2000123200ff1200
Received response from port: 0001000500000000
Received response from port: 0000000020000000
Received response from port: 1251000012455222
Received response from port: 446174613a206365
Received response from port: 6369206573742075
Received response from port: 6e20746573743b90
由于我使用的是API模式,因此无法像在其他解决方案中所看到的那样,发送结束定界符来指定数据包的结尾(请参阅Java完整行串行端口 )。
我当时在考虑使用下一个数据包的开始分隔符,但是没有成功。
我用api数据包的长度弄清楚了。 由于长度在第一个数组的[1]和[2]位置,因此我可以使用该值在接收数据时继续构建数据包。 当我的msgLengthLeft值为0时,我知道该数据包已全部收到,并且我可以返回完整的数据包。 这是我的代码:
private static class PortReader implements SerialPortEventListener {
private short msgLength;
private short msgLengthLeft;
private byte[] receivedMsg = new byte[packetSize];
ByteArrayOutputStream outputStream = new ByteArrayOutputStream( );
@Override
public void serialEvent(SerialPortEvent event) {
if(event.isRXCHAR() && event.getEventValue() > 0) {
try {
byte[] receivedData = serialPort.readBytes(event.getEventValue());
if(Utils.isConfirmPacket(Utils.toHex(receivedData))){
System.out.println("XBee confim that msg is sent!");
}else{
if(receivedData[0] == 0x7e){ //0x7e is the start delimiter of a frame
ByteBuffer wrapped = ByteBuffer.wrap(receivedData,1,2); // big-endian by default
msgLength = (short) (wrapped.getShort()+4); //Need to add 4 to the value becaus some field are not include in the length field of the api packet
msgLengthLeft = (short) (msgLength - receivedData.length);
outputStream.write(receivedData);
return;
}else{
msgLengthLeft = (short) (msgLengthLeft - receivedData.length);
outputStream.write(receivedData);
if(msgLengthLeft != 0){
return;
}
}
System.out.println("Received response from port: " + Utils.toHex(outputStream.toByteArray( )));
int dataLength = Utils.toHex(receivedMsg).length();
//receiveFile("testRx", receivedData, dataLength);
}
}
catch (SerialPortException | IOException ex) {
System.out.println("Error in receiving response from port: " + ex);
}
}
}
}
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