I am using this example to communicate between arduino and android, and it works well.
The problem is that i would make sure all data has been received before outputting it.
As it is now android will simply output everything when it is being received.
I need to collect whatever is received so that i for example can compare it to another string.
Currently it works like this
UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() { //Defining a Callback which triggers whenever data is read.
#Override
public void onReceivedData(byte[] arg0) {
String data = null;
try {
data = new String(arg0, "UTF-8");
data.concat("/n");
tvAppend(textView, data);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
};
And arduino:
void setup()
{
Serial.begin(9600);
}
void loop()
{
char c;
if(Serial.available())
{
c = Serial.read();
Serial.print(c);
}
}
Example:
Sent to arduino:
TEST
Received from arduino:
TEST
However in reality its more like this
Sent to arduino:
TEST
Received from arduino:
T E ST
So the received "TEST" will come in bytes of one or two which then needs to be gathered into a string.
I assume the reason for this is due to the rate/speed of incoming bytes so that it will just output it as soon as it gets the data.
I would like to make sure that all incoming data is received before I output it, so that I can work with the incoming data.
In theory in need something like while(serial.available())... for android.
Any help is appreciated
Related
I would like to create an application which can connect to a Bluetooth Headset via the Hands Free Protocol (HFP). I followed the Android example and have now a BluetoothSocket with its Input and OutputStream. Below you see my read and write methods (read method is executed by another Thread)
public void read() {
while (true) {
Log.d("ME", "Waiting for data");
try { // read until Exception is thrown
numBytes = inStream.read(dataBuffer);
String str = new String(dataBuffer,0,numBytes);
msgHandler.obtainMessage(numBytes, str).sendToTarget();
} catch (Exception e) {
Log.d("ME", "Input stream was disconnected", e);
break; // BluetoothDevice was disconnected => Exit
}
}
}
public void write(byte[] bytes) {
try {
outStream.write(bytes);
outStream.flush();
Log.e("ME", "Wrote: " + new String(bytes));
} catch (IOException e) {
Log.e("ME", "Error occurred when sending data", e);
}
}
When the connection is opened the Bluetooth headset sends AT+BRSF=191 over the InputStream. I tried to response with +BRSF:20\r but here is my problem. After that the device does not send any other data over the InputStream. It does not come to an Exception - it's more like the device does not know how to responde to my message. Do I send the wrong data? I have all the information from here: (HF = Hands-Free Unit AG = Audio Gateway)
Do you have any ideas what I did wrong? Have I missed something?
EDIT: These are my write calls:
write("+BRSF: 191\r");
write("OK\r");
You were missing the OK response. According to this document, the OK-code consists of a windows-style newline (CR LF), the literal OK and then another newline.
Do note that other commands are terminated by a carriage return only. For more information on the hands-free protocol, you can refer to that very document you linked in your post.
Example code:
public static final String OK = statusCode("OK")
public static final String ERROR = statusCode("ERROR")
public static String statusCode(String code) {
return "\r\n" + code + "\r\n";
}
public static String command(String cmd) {
return cmd + "\r";
}
Now you can use OK and ERROR in your code as constants, and you can use the statusCode method for other status codes.
Is there a way to log the binary data send to the tranceive method of a NFC tag? https://developer.android.com/reference/android/nfc/tech/NfcV.html#transceive(byte[])
I am trying to find the last few missing pieces in a protocol and it would help if I could listen to the data getting sent.
I'm guessing that:
You want to monitor the APDUs/bytes sent from an app you have installed.
You've already searched for info about that specific protocol and found nothing.
At the Logcat, no relevant info is shown (by default).
Looking up at the transceive source code
public byte[] transceive(byte[] data) throws IOException {
return transceive(data, true);
}
which redirects to:
byte[] transceive(byte[] data, boolean raw) throws IOException {
checkConnected();
try {
TransceiveResult result = mTag.getTagService().transceive(mTag.getServiceHandle(),
data, raw);
if (result == null) {
throw new IOException("transceive failed");
} else {
return result.getResponseOrThrow();
}
} catch (RemoteException e) {
Log.e(TAG, "NFC service dead", e);
throw new IOException("NFC service died");
}
}
Which goes on to the TransceiveResult class.
My best bet (if you wish to get to the very end) is to recompile an Android source code that prints out the data input'd to the byte[] transceive(byte[] data) function. Good luck.
EDIT: Another option I happened to realise is to use an APDU sniffer, although I legitimately don't know how legal this option is.
I am developing Client-Server application in C++ using Qt framework, but the clients can be android phones and computers(Qt client app)
Now i'm having troubles to handle Reception of data on the server side; the server is not receiving data properly.
First, I got things working nicely between the server(Qt app) and the client(Qt app) using these methods for sending and receiving:
The size of the message is kept at the beginning of the packet to help check whether the whole message is received or not.
This is the method to send message to the clients
void Server::send(const QString &message)
{
QByteArray paquet;
QDataStream out(&paquet, QIODevice::WriteOnly);
out << (quint16) 0; // just put 0 at the head of the paquet to reserve place to put the size of the message
out << message; // adding the message
out.device()->seek(0); // coming back to the head of the paquet
out << (quint16) (paquet.size() - sizeof(quint16)); // replace the 0 value by the real size
clientSocket->write(paquet); //sending...
}
This slot is called every time a single paquet is received.
void Server::dataReceived()
{
forever
{
// 1 : a packet has arrived from any client
// getting the socket of that client (recherche du QTcpSocket du client)
QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
if (socket == 0)
return;
QDataStream in(socket);
if (dataSize == 0) // if we don't know the size of data we are suppose to receive...
{
if (socket->bytesAvailable() < (int)sizeof(quint16)) // we haven't yet receive the size of the data completly then return...
return;
in >> dataSize; // now we know the amount of data we should get
}
if (socket->bytesAvailable() < dataSize)
return;
// Here we are sure we got the whole data then we can startreadind
QString message;
in >> message;
//Processing....
dataSize = 0; // re-initialize for the coming data
}
}
This is working well when the server is talking with the Qt app Client, because the same methods are used there, and the size of quint16 will remain the same hover it doesn't work with android client, then i tried another way in which i wanted to ignore the size of the message sent, but format the message in a way such that i can know where it starts and where it ends, then with some controls i can get it however i'm stuck here, cause the data read doesn't contain anything when printed, but his size has a value(which even vary according to the amount of text the client send)!
void Server::dataReceived() // a packet is received!
{
QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
if (socket == 0)
return;
QByteArray data= socket->readAll(); //reading all data available
QString message(data)
qDebug() << data; // this prints nothing!
qDebug() << data.size();// But this prints a non null number, wich means we got something, and that number varies according to the amount of text sent!
qDebug() << message; // this also prints notghing!
}
PS: it's not working even for the Qt app Client.
Can you help me find out what's wrong, i'm a bit confused how the tcp protocol is handling the data, and if you could and also advise me a good way for doing this.
here is the android class I made for the purpose
class QTcpSocket implements Runnable {
private String ip="";
private int port;
private Socket socket;
private PrintWriter printWriter;
private DataOutputStream dataOutputStream;
private DataInputStream dataInputStream;
public QTcpSocket(String ip, int port) {
this.ip = ip;
this.port = port;
}
public void setIp(String ip) {
this.ip = ip;
}
public String getIp() {
return this.ip;
}
public void setPort(int port) {
this.port = port;
}
public void run() {
try {
socket = new Socket(this.ip, this.port);
dataOutputStream = new DataOutputStream( socket.getOutputStream() );
dataInputStream = new DataInputStream(socket.getInputStream());
String response = dataInputStream.readUTF();
dataOutputStream.writeUTF("Hello server!");
} catch (IOException e) {
e.printStackTrace();
}
}
public void sendMessage(String message) {
try {
dataOutputStream.writeUTF(message);
}catch (IOException e) {
e.printStackTrace();
}
}
public void disconnect() {
try {
printWriter.flush();
printWriter.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public boolean isClosed() {
return socket.isClosed();
}
}
Replace in 'data' all bytes with value 0 by value 20 and print again. I think you see nothing printed because the first byte is 0. You could also replace with 'X'. Did you already replace writeUTF() by write() ?
20 is the space character. But then you also see nothing printed so better use a X char. Strings get printed until a \0 char (which indicates the end of a string) is met. Because nothing was printed i supposed one right at the beginning. So writeUTF causes that leading 0. I could only explain that if all chars had doubled. What was the first char you sent?
But now: send size-of-message first so it equals your qt client.
I'm developing an Android real-time-data app that sends data (floats and ints) to a server on the local subnet via a TCP socket. The problem I'm facing is that after sending some data simultaneously the socket doesn't send anymore data at all. I debugged the app and it shows that data is being sent but doesn't show up on the server. After this happens if I close the connection the server doesn't even get the notification that the connection has been terminated which it should according to my design model. Meanwhile I get an exception on the app saying it can not write to a broken pipe. This tells me that the problem is with the app because I also did test using a desktop app and I can send huge amounts of data to the server and it gets delivered.
And please keep in mind that the data size I'm talking about here is 252 bytes per packet.
Here's my class I'm using. (This runs in an AsyncTask object )
public class Network
{
private Socket handle;
public static enum TASK
{
TASK_CONNECT, TASK_SEND, TASK_CLOSE
}
public Network()
{
}
public String lastError = "";
public boolean Connect(String host, int port)
{
try
{
lastError = "Connecting to server.";
handle = new Socket(host, port);
handle.setTcpNoDelay(true); //
handle.setSendBufferSize(SIZE_OF_PACKET); ///==> These don't seem to help at all
handle.setKeepAlive(true); ///
return true;
}catch(IOException e)
{
lastError += e.getMessage() != null ? " "+ e.getMessage() : "";
return false;
}
}
private void err(String e){
System.err.println(e);
}
private boolean SendPacket(byte buffer[])
{
OutputStream oStream = null;
err("sending: " + buffer.length + " bytes");
try
{
lastError = "Obtaining output stream.";
oStream = handle.getOutputStream();
lastError = "Error sending data.";
oStream.write(buffer);
oStream.flush();
return true;
}catch(Exception e)
{
lastError += e.getMessage() != null ? " "+ e.getMessage() : "";
}
return false;
}
public void Close()
{
try{ handle.close(); handle = null; }catch(Exception e){} // swallow exception
}
}
I send my data in a loop depending on how many numbers I have. I tried a Google search but didn't find anything relevant. Has anyone experienced this before? It's making me mad now.
EDIT: Wireshark shows incoming "red" packets that don't reach the desktop app (server)
Look at this picture.
You can see the first few have Len > 0 the red ones have 0.
I think it's time Google interfaced the USB so we can use it. At least that'd would have been my first option.
Should you not be calling oStream.close() after you flush the stream, given that you never use it again?
Also, you say that this is being run in an AsyncTask object. Is it possible that multiple threads could be attempting to send packets at the same time? If so, you might need some form of synchronisation around the SendPacket method.
Ok. I solved the issue by using UDP instead. Thank you all.
But I still didn't find the source of the problem.
I've been having an issue with data integrity using an RFCOMM socket over Bluetooth in Android. I don't have any issues connecting, but the data I receive is garbled and not the same as the data that is sent. The data is sent by an RS232 device over a Bluetooth adapter, which the phone connects to. There isn't a problem with the adapter as the data is properly received if I connect with a laptop.
My Bluetooth connection is handled based off of the BluetoothChat sample application found at the Android developer site (http://developer.android.com/resources/samples/BluetoothChat/index.html), with no changes. The data being sent is plain text and control characters (which are stripped out before display to the user). The specific problem I have is that some of the text is missing, some of it is repeated, etc.
The funny thing is if I connect to a computer with a terminal app and type in there, the data is transmitted fine. Additionally, if I connect to the device using the GetBlue app the data is received fine.
So I guess the issue is what does GetBlue possibly do different to handle its Bluetooth data transfer, or is there another way receive Bluetooth data over an RFCOMM socket on Android?
The fix for the solution was to create the string in the connected thread, directly after calling read() on the InputStream, and then passing the string back to the main thread for display. For whatever reason, passing the byte array between threads led to significant repetition and data loss.
Modified run() code:
public void run() {
byte[] buffer = new byte[256]; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
String readMessage = new String(buffer, 0, bytes);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, readMessage)
.sendToTarget();
} catch (IOException e) {
break;
}
}
}
And the handler reception:
case MESSAGE_READ:
// Read in string from message, display to mainText for user
String readMessage = (String) msg.obj;
if (msg.arg1 > 0) {
mainText.append(readMessage);
}
This error is because the object reference is passed to the UI, If you copy the byte array(buffer) to another byte array it works.