Develop Reference

HC-05 + Android ( Wrong echos / data )

So I am facing a problem from a while now . Any suggestion would be good.
First I used my code to receive data from arduino , then I used the bluetoothChat and changed the uuid , I can pair , everything is good , but if I send an entire string from arduino to android I get only parts of that string.
If I use bluetooth terminal from google play everything is ok, and on the description it says it is made from the bluetooth Chat sample .
Code Arduino
#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 9); //RX,TX
long int i = 0;
void setup(){
mySerial.begin(9600);
}
void loop(){
mySerial.print("This is a message n. ");
mySerial.println(i);
i++;
delay(100);
}
Android code : Bluetooth Chat Sample
Exemple of message received on Android:
Message to be sent!
So first messages I think are waiting while the module is paired .
because every time I get .
is is a message n. 466
This is a message n.467
.
. ( here I get correct messages )
.
This is a message n.470
message n. 495
.
.
and after the first messages I get messages like
ssage n.534
t
essage n.m
essage n.
535
( I neved again get an entire message )
Handler :
h = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case RECIEVE_MESSAGE: // if receive massage
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1); // create string from bytes array
sb.append(strIncom); // append string
int endOfLineIndex = sb.indexOf("\r\n"); // determine the end-of-line
if (endOfLineIndex > 0) { // if end-of-line,
String sbprint = sb.substring(0, endOfLineIndex); // extract string
sb.delete(0, sb.length()); // and clear
Log.d("Arduino", "Mesaj:"+ sbprint.toString());
}
Log.d("Arduino", "...Mesaj:"+ sb.toString() + " Byte:" + msg.arg1 + "...");
break;
}
};
};
Listener to InputStream
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); // Get number of bytes and message in "buffer"
h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget(); // Send to message queue Handler
} catch (IOException e) {
break;
}
}
}

note you are using a software emulation of serial port, hence timing is not as good as it would be with a hardware UART.
It is likely one or both of the following two possible issues:
1) the start and stop bit are not properly timed, causing back to back bytes. Which occur when a string is set, rather then pecking in keys one at a time.
The solution would be to space out each key.
2) baud rates do not match with in tolerance. Either SLOWING DOWN or SPEEDING UP the baud rate on both the HC05 and Arduino will better match the timing.
I would also recommend ensuring your library is SoftwareSerial, states that it is NewSoftSerial. It has many issues fixed. It was implemented in to the Arduino IDE 1.0.+ core libraries, so if you have recent IDE you should have it.

Android NfcA Transceive fails on success

I made a simple test application for quick debugging. I send some bytes, print what I sent on the phones screen and print what I receive.
When I send WRONG commands I get the corresponding error codes in the two byte SW1SW2.
I can also call my own command and override SW1SW2 with my own values and I can get them.
Here's the problem: When I send a CORRECT command the transceive command fails with the informative exception "Transceive failed".
If I send the correct command, but override SW1SW2 to something other than 90 00 then I get the SW value I set, but NO response data. (likely because the card does not send ODATA when SW1SW2 <> 90 00)
So how come I'm so sure I sent correct commands? Well other than messing with my own test command I called the GetAppId command - which failed saying I have to define AppId in the card.
So I define it in the card, send the same command and transceive fails.
So I'm pretty sure the problem is that transceiving fails when there is ODATA, but I do not understand WHY or how to FIX it.. help please!
EDIT: My card is the 7.5 D contactless basiccard from ZeitControl.
EDIT2: I have set the timeout to 2000ms with no change in behavior. I'm trying to return a single byte of data and the system command I called also doesn't sound heavy.
Then I downloaded and attached the Android source and debugged. There was some segments it would still not go into - but the card seems to return null on valid commands unless I return some manually set SW1SW2 in which case that is the only thing received.
EDIT3: The system command I tried was:
192 14 0 0 0
(or C0 0E 00 00 00)
(or CLA INS P1 P2 Lc)
I'm not 100% sure I'm doing that one correctly, but I have tried with various lengths (up to 22) of Le and without Le as above and only without does it not give me 6700 (wrong Le/Lc)
Of course instead of 6700 it returns null it seems...
The other command is my own defined as 20 0A (value as Byte) and no P1/P2 specified in the .BAS file.
I call that one with:
32 10 1 0 1
(or 20 0A 01 00 01)
(or CLA INS Lc IDATA Le)
This should mean 1 byte data in, set to 0, and 1 byte expected out (+ SW1/SW2 as always).
(Setting P1/P2 gives 6700 so unless defined in the command declaration I dont think they should be there)
This also returns null. I Expect 00 90 00 to be returned here. (if I set "value" to 00 that is)
I'm using a HTC One X.
EDIT4:
MinSdk version = 14 and target 18.
if(bitcoinCard != null){
try {
String sentmsg, receivedmsg;
byte[] send = getBytes(commandBytes.getText().toString());
byte[] data = null;
if(send != null){
bitcoinCard.setTimeout(2000);
data = bitcoinCard.transceive(send);
}
//bitcoinCard.close();
/*if(data != null && data.length == 2)
{
mainLabel.setText("SW1SW2: " + (data[0] < 0 ? -data[0] +
128 : data[0]) + " " + (data[1] < 0 ? -data[1] + 128 : data[1]));
}else */if (data != null && send != null)
{
sentmsg = "" + (send[0] < 0 ? send[0] + 256 : send[0]);
for(int i = 1; i < send.length; i++)
{
sentmsg = sentmsg + " " + (send[i] < 0 ? send[i] +
256 : send[i]);
}
receivedmsg = "" + (data[0] < 0 ? data[0] + 256 : data[0]);
for(int i = 1; i < data.length; i++)
{
receivedmsg = receivedmsg + " " + (data[i] < 0 ? data[i] + 256 : data[i]);
}
mainLabel.setText("Sent: " + sentmsg + "\n" +
"Response: " +
receivedmsg);
}else
{
mainLabel.setText("Sent or received null.");
}
} catch (IOException e) {
mainLabel.setText("Tried to talk to card, but had error: " +
e.getMessage());
}
}

First, when you send APDUs you should use an IsoDep object (and not NfcA). Android should show both tag technologies as available for your card. The problem here is that Android will typically only activate the card in ISO 14443-4 protocol mode if you use IsoDep. Thus, wehn using NfcA, your card will not be ready to accept APDUs.
I just tested and this is at least the case on a Nexus S with Android 4.1.2. In fact trying to transceive using the NfcA object leads to TagLostExceptions with some cards and to some other really odd behavior with another card I tried.
Second, if you send
byte[] cmd = { (byte)0xC0, (byte)0x0E, (byte)0x00, (byte)0x00, (byte)0x00 };
I would expect the card to return the actual application ID. However, the answer to this command (i.e. <data> <SW1=61> <SW2=len>) does not comply to ISO 7816-4 (no data should be returned for a 61xx status code) so this might cause a problem.
UPDATE: I just tested this with a Nexus S (Android 4.1.2) and receiving such responses was not a problem.
Last, your other command (20 0A) is not what you expect it to be:
I strongly suggest you only use CLA bytes set to 0x00 or 0x80 unless you know what you are doing (use of secure messaging, use of logical channels, ...). Though, Android (at least with NXP's NFC chipset) does not care about the structure of the APDU, but your card might!
An APDU always has the form <CLA> <INS> <P1> <P2> [Lc [DATA]] <Le> (with the special case of <CLA> <INS> <P1> <P2>). So this means you cannot simply omit P1 and P2.
You are correct in that BasicCard will discard ODATA if SW<>9000 and SW1<>61.

Why is data from Arduino to Android using Android host api garbled?

I followed this tutorial to get started using Android host api with an Arduino board. I am using the Arduino Uno. I am able to transmit data and turn on a LED on the Arduino board and I can receive feedback from the Arduino board. I am trying to write to my Android device over the USB connection from the Arduino board like so:
Serial.print("Test");
I am receiving the Arduino data on the Android side like this:
byte[] buffer = new byte[10];
int bytes;
//try-catch statements omitted for simplicity
bytes = mUsbConnection.bulkTransfer(mUsbEndpointIn, buffer, buffer.length, 0);
Every once and awhile the data will be intact but more often than not, what I receive from the Arduino is a garbled mix of those letters from my original message(t,e,s, and t). Many times only 1 or 2 letters are displayed. If anyone could point me in the right direction or share some similar experience I would be appreciative. Thanks.
Edit
When I print out the data into Logcat, there are multiple copies of the data. For example, if I receive "ste" from Arduino, it will be printed out 2-5 times in Logcat.

I think I found something that works at least temporarily:
public void run(){
int i = 0;
byte[] buffer = new byte[4];
byte[] finalBuffer = new byte[8];
byte[] sendBuffer = new byte[8];
int bytes = 0;
while(true){
try{
bytes = mUsbConnection.bulkTransfer(mUsbEndpointIn, buffer, buffer.length, 0);
if (bytes == EXIT_CMD) {
return;
}
if (bytes > 0){
byte[] temporaryBuffer = new byte[bytes];
System.arraycopy(buffer, 0, temporaryBuffer, 0, bytes);
System.arraycopy(temporaryBuffer, 0, finalBuffer, i, bytes);
i += bytes;
java.util.Arrays.fill(buffer, (byte) 0);
}
//Dollar sign terminates string to indicate end of line
if (finalBuffer[7] == 36){
i = 0;
System.arraycopy(finalBuffer, 0, sendBuffer, 0, sendBuffer.length);
messageHandler.obtainMessage(UsbHostTestActivity.ARDUINO_MESSAGE,
sendBuffer.length, -1, sendBuffer).sendToTarget();
java.util.Arrays.fill(finalBuffer, (byte) 0);
}
I had to send strings that were 8 characters exactly from Arduino and they had to end with a dollar sign($) in order to indicate the end of the line, but the data being passed to my message handler always seemed to be correct. It's not the most robust solution but maybe someone can modify it to make it better or take another approach? Please let me know!

Byte Dropped Over Bluetooth Connection in Android

I am having some issues with bytes being dropped over a bluetooth connection between an android device (Gingerbread 2.3.1) and a PC. The way I receiving the data is in a 2 byte buffer. The values being received is streaming from the PC over a few minutes (values represent a waveform). Here are just a few snippets of code so you can get the idea. The base of my code is from the android bluetooth chat sample code.
BluetoothSocket socket;
...
mmInStream=socket.getInputStream;
...
byte[] buffer= new byte[2];
...
bytes = mmInStream.read(buffer);
Has anyone has issues with this type of thing? The dropped bytes seem to happen at random times while at other times the values received are as expected. I am using a 2 byte buffer because the values I am receiving are 16 bit signed integers. From the PC side of things I am using RealTerm to send the binary files of data.
Is it possible that my buffer is too small and that is causing the dropped bytes?
Thanks

Following up to your answer. You could just use a counter to remember how many bytes already read and compare it to the number wanted and also use it for the index to write the next byte(s). See a C# version at http://www.yoda.arachsys.com/csharp/readbinary.html
public static void ReadWholeArray (Stream stream, byte[] data)
{
int offset=0;
int remaining = data.Length;
while (remaining > 0)
{
int read = stream.Read(data, offset, remaining);
if (read <= 0)
throw new EndOfStreamException
(String.Format("End of stream reached with {0} bytes left to read", remaining));
remaining -= read;
offset += read;
}
}

I have found what the issue is. I want to thank alanjmcf for pointing me in the right direction.
I wasn't checking by bytes variable to see how many bytes were returned from the mmInStream.read(buffer). I was simply expecting that every buffer returned would contain 2 bytes. The way i solved the issue was with the following code after getting the buffer back from the InputStream:
//In the case where buffer returns with only 1 byte
if(lagging==true){
if(bytes==1){
lagging=false;
newBuf=new byte[] {laggingBuf, buffer[0]};
ringBuffer.store(newBuf);
}else if(bytes==2){
newBuf=new byte[] {laggingBuf, buffer[0]};
laggingBuf=buffer[1];
ringBuffer.store(newBuf);
}
}else if(lagging==false){
if(bytes==2){
newBuf = buffer.clone();
ringBuffer.store(newBuf);
}else if(bytes==1){
lagging=true;
laggingBuf=buffer[0];
}
}
This fixed my problem. Any suggestions on a better methodology?

Android getInputStream() does not retrieve all bytes, but only sporadically

First, I have a class that extends AsyncTask. Then in the doInBackground() method, I have some code that posts an HTTP post message, and gets a response. This response is read into a string as follows:
DataInputStream dis = new DataInputStream(conn.getInputStream());
byte[] data = new byte[32768];
len = dis.read(data, 0, 32768);
if (len > 0)
{
response = new String(data, 0, len);
}
At this point, response should be 4127 bytes (as confirmed by the server). 1/5th of the time it IS 4127 bytes. 2/5 of the time it's 1205 bytes, and 2/5 of the time it's 3853 bytes. I can close the app, reinstall, and I get the same variation.
The person who manages the server logs everything and can confirm the same data is being sent over and over. But Android isn't getting the full stream. This is wireless, not 3g. When I use the debugger, I can see that the string returned is always identical, just chopped off at a random spot.
Sorry for such a vague (stupid?) question, but I've been looking at this for hours and I can't see what's wrong with it...

The read method documentation says: Reads up to len bytes of data from the contained input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.
Depending on different conditions, sometimes you can read all server-sent data, sometimes there is a short-read. In order to get all data you should keep reading the stream in a loop until len is -1, indicating an EOF.
InputStream in = ...;
byte[] dst = new byte[32768]; /* Assuming total len is < 32768 */
int idx = 0;
do {
int len = in.read(dst, idx, 32768 - idx);
idx += len;
} while (len >= 0 || idx < 32768);