Develop Reference

Transfer Image throug BLE in android

I'm transfering an image of 1 mb using the following code.
The image gets transferred successfully if a thread delay is implemented between each packets.
If the thread delay is not set all the packets are sent from BluetoothGattServer but the BluetoothGattCallback does not receive all the packets.
Can anyone guide in sending the packets without the thread delay
Implement thread between each packets
private void sendingContinuePacket(BluetoothGattCharacteristic characteristic,
byte[] CHARACTERS) {
boolean isComplete = false;
runOnUiThread(() -> {
tv_status.setText("Sending Data...!!");
startTime = SystemClock.uptimeMillis();
customHandler.postDelayed(updateTimerThread, 0);
});
// Check the data length is large how many times with Default Data (BLE)
int times = CHARACTERS.length / DEFAULT_BYTES_IN_CONTINUE_PACKET;
totalPackets = times;
Log.i("", "CHARACTERS.length() " + CHARACTERS.length);
byte[] packetNoByte;
byte[] sending_continue_hex = new byte[DEFAULT_BYTES_IN_CONTINUE_PACKET];
for (int time = 0; time <= times; time++) {
final int remainingTime = time;
if (!hasDisconnected) {
this.runOnUiThread(new Runnable() {
#Override
public void run() {
mRelativeLayout.setVisibility(View.VISIBLE);
if (totalPackets != 0) {
showProgress(totalPackets, remainingTime);
}
}
});
} else {
runOnUiThread(() -> {
mProgressBar.setProgress(0);
tv_progress.setText(0 + "%");
tv_timer.setText("00:00:00");
tv_imageSize.setText("");
tv_status.setText("");
Toast.makeText(PeripheralRoleActivity.this, "Something went wrong, Please Try again", Toast.LENGTH_SHORT).show();
customHandler.removeCallbacks(updateTimerThread);
});
return;
}
int a;
int b;
/**
* #param THREAD_SLEEP_TIME_FOR_NOTIFICATION
* this delay is placed to give a small pause while sending the data packe
* */
try {
Thread.sleep(Constants.THREAD_SLEEP_TIME_FOR_NOTIFICATION);
} catch (InterruptedException e) {
e.printStackTrace();
}
sentPacket = sentPacket + 1;
byte[] packetArray = Utils.getUtilsClass().toByteArray(sentPacket);
packetNoByte = Arrays.copyOf(packetArray, packetArray.length);
if (time == times) {
Log.i("", "LAST PACKET ");
int character_length = CHARACTERS.length
- DEFAULT_BYTES_IN_CONTINUE_PACKET * times;
byte[] sending_last_hex = new byte[character_length];
a = (sending_continue_hex.length) * time;
b = a + character_length;
if(b-a ==0){
return;
}
sending_last_hex = Arrays.copyOfRange(CHARACTERS, a, b);
byte[] last_packet =
new byte[packetNoByte.length + character_length];
System.arraycopy(packetNoByte, 0, last_packet,
0, packetNoByte.length);
System.arraycopy(sending_last_hex, 0, last_packet,
packetNoByte.length, sending_last_hex.length);
Log.d("Sending packets", Arrays.toString(last_packet));
// Set value for characteristic
characteristic.setValue(last_packet);
notifyCharacteristicChanged();
isComplete = true;
customHandler.removeCallbacks(updateTimerThread);
currentDateTimeString = DateFormat.getDateTimeInstance().format(new Date());
Log.d("Collection", "End Time: " + currentDateTimeString);
Utils.getUtilsClass().sendNotification(getApplicationContext(), "Data Transfer", "Transfer Complete");
} else {
Log.i("", "CONTINUE PACKET ");
a = ((sending_continue_hex.length) * time);
b = a + DEFAULT_BYTES_IN_CONTINUE_PACKET;
sending_continue_hex = Arrays.copyOfRange(CHARACTERS, a, b);
byte[] sending_continue_packet =
new byte[packetNoByte.length + sending_continue_hex.length];
System.arraycopy(packetNoByte, 0, sending_continue_packet,
0, packetNoByte.length);
System.arraycopy(sending_continue_hex, 0, sending_continue_packet,
packetNoByte.length, sending_continue_hex.length);
Log.d("data transfer a", String.valueOf(a));
Log.d("data transfer b", String.valueOf(b));
Log.d("data trans bytes", String.valueOf(sending_continue_hex.length));
if(output == null){
output = new ByteArrayOutputStream();
}
try {
if {
characteristic.setValue(sending_continue_packet);
Log.d("Sending packets", Arrays.toString(sending_continue_packet));
notifyCharacteristicChanged();
}
} catch (IOException e) {
e.printStackTrace();
}
}
Log.d("Data byte", "times " + time);
if (isComplete) {
characteristic.setValue("Completed");
notifyCharacteristicChanged();
}
runOnUiThread(() -> tv_status.setText("Data sent!!"));
}
}
Updated Code
//the following function is used break the image byte [] into packets and store it in an arraylist
private void breakPackets(byte[] CHARACTERS) {
// Check the data length is large how many times with Default Data (BLE)
int times = CHARACTERS.length / DEFAULT_BYTES_IN_CONTINUE_PACKET;
totalPackets = times;
packetList = new ArrayList<>();
sendingPacket = 0;
Log.i("", "CHARACTERS.length() " + CHARACTERS.length);
byte[] sending_continue_hex = new byte[DEFAULT_BYTES_IN_CONTINUE_PACKET];
for (int time = 0; time <= times; time++) {
int a;
int b;
if (time == times) {
Log.i("", "LAST PACKET ");
int character_length = CHARACTERS.length
- DEFAULT_BYTES_IN_CONTINUE_PACKET * times;
byte[] sending_last_hex = new byte[character_length];
a = (sending_continue_hex.length) * time;
b = a + character_length;
sending_last_hex = Arrays.copyOfRange(CHARACTERS, a, b);
//packetList is an ArrayList<byte[]>
packetList.add(sending_last_hex);
startSendingPackets(sendingPacket);
} else {
a = (sending_continue_hex.length) * time;
b = a + DEFAULT_BYTES_IN_CONTINUE_PACKET;
sending_continue_hex = Arrays.copyOfRange(CHARACTERS, a, b);
packetList.add(sending_continue_hex);
}
Log.d("Data byte", "times " + time);
}
}
//the following function is used to set the byte[] from the arraylist to the characteristics and then notify the characteristics
private void startSendingPackets(int packet) {
isCommand = false;
mSampleCharacteristic.setValue(packetList.get(packet));
notifyCharacteristicChanged();
Log.i("packeting", "Sending ------------> " + packet);
}
/*************************************************/
#Override
public void onNotificationSent(BluetoothDevice device, int status) {
super.onNotificationSent(device, status);
//check if status is success
if (status == BluetoothGatt.GATT_SUCCESS) {
//if status is not successful isExecutable is false and the else loop is executed to resend the same packet that has failed
if (isExecutable) {
// Log.i("packeting", "Sent ------------> " + sendingPacket);
sendingPacket = sendingPacket + 1;
int size = packetList.size();
if (sendingPacket <= size-1) {
startSendingPackets(sendingPacket);
Log.d(MainActivity.TAG, "Notification sent. Status: " + status + " sending packet no --" + sendingPacket);
} else {
sendCommand("Completed");
}
} else {
startSendingPackets(sendingPacket);
isExecutable = true;
Log.d(MainActivity.TAG, "Notification sent. Status: " + status + " sending packet no --" + sendingPacket);
}
}else{
//if status is not successful
isExecutable = false;
Log.d(MainActivity.TAG, "Notification sent. fail Status: " + status );
}
}

As can be read in the documentation at https://developer.android.com/reference/android/bluetooth/BluetoothGattServerCallback.html#onNotificationSent(android.bluetooth.BluetoothDevice,%20int):
When multiple notifications are to be sent, an application must wait
for this callback to be received before sending additional
notifications.
This means after you have called notifyCharacteristicChanged, you cannot call notifyCharacteristicChanged again until the callback onNotificationSent has been received. So you need to remove your for-loop and refactor your code to follow the API rules.
The reason for this is to get flow control. If you just push new packets faster than the BLE link's throughput, the internal buffers get full and packet loss will occur. That's why a delay might seem to work, but it's not a robust solution so that's why you should wait for the onNotificationSent callback since that means the BLE stack is ready to accept new packets.

Using AudioRecord.read and always getting buffer with maximum amplitudes

I'm trying to record audio and detect silence to stop recording and write file. Below is the code snippet already available here: Android audio capture silence detection
public class RecordAudio extends AsyncTask<Void, Double, Void> {
#Override
protected Void doInBackground(Void... arg0) {
Log.w(TAG, "doInBackground");
try {
String filename = getTempFilename();
try {
os = new FileOutputStream(filename);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
bufferSize = AudioRecord.getMinBufferSize(frequency,
channelConfiguration, audioEncoding);
AudioRecord audioRecord = new AudioRecord( MediaRecorder.AudioSource.MIC, frequency,
channelConfiguration, audioEncoding, bufferSize);
short[] buffer = new short[bufferSize];
audioRecord.startRecording();
while (started) {
int bufferReadResult = audioRecord.read(buffer, 0,bufferSize);
if(AudioRecord.ERROR_INVALID_OPERATION != bufferReadResult){
//check signal
//put a threshold
int foundPeak = searchThreshold(buffer,threshold);
if (foundPeak >- 1) { //found signal
//record signal
byte[] byteBuffer =ShortToByte(buffer,bufferReadResult);
try {
os.write(byteBuffer);
} catch (IOException e) {
e.printStackTrace();
}
} else {//count the time
//don't save signal
Log.d(TAG, "Silence...");
}
} else {
Toast.makeText(getBaseContext(), "Error!!!!", Toast.LENGTH_SHORT).show();
}
}
audioRecord.stop();
//close file
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
copyWaveFile(getTempFilename(),getFilename());
deleteTempFile();
} catch (Throwable t) {
t.printStackTrace();
Log.e("AudioRecord", "Recording Failed");
}
return null;
}
byte [] ShortToByte(short [] input, int elements) {
int short_index, byte_index;
int iterations = elements; //input.length;
byte [] buffer = new byte[iterations * 2];
short_index = byte_index = 0;
for(/*NOP*/; short_index != iterations; /*NOP*/)
{
buffer[byte_index] = (byte) (input[short_index] & 0x00FF);
buffer[byte_index + 1] = (byte) ((input[short_index] & 0xFF00) >> 8);
++short_index; byte_index += 2;
}
return buffer;
}
int searchThreshold(short[]arr,short thr){
int peakIndex;
int arrLen=arr.length;
for (peakIndex=0;peakIndex<arrLen;peakIndex++){
if ((arr[peakIndex]>=thr) || (arr[peakIndex]<=-thr)){
Log.d(TAG, String.valueOf(arr[peakIndex]) + " - " + String.valueOf(peakIndex));
return peakIndex;
}
}
return -1; //not found
}
The problem is I'm not able to detect silence in the signal. Every time I read the buffer I get values greater than 32000 or less than -32000 (which I interpreted as maximum possible amplitudes for the signal, since the buffer is made up of short integer values), even when there is silence, so the threshold that determines what is "noise" and what is silence is always reached, and the searchThreshold function never returns -1.
Did anyone experience the same? I'm using a Samsung S5 device for tests.
Thanks in advance

In fact, values near 32000 or -32000 in buffer represents silence, and the values tends to zero when signal is detected. So I inverted the conditions inside searchThreshold function as below and I achieved what I was looking for.
int searchThreshold(short[]arr,short thr_upper, short thr_lower){
int peakIndex;
int arrLen=arr.length;
for (peakIndex=0;peakIndex<arrLen;peakIndex++){
if ((arr[peakIndex] <= thr_upper) && (arr[peakIndex] >= thr_lower )){
return peakIndex;
}
}
return -1; //not found
}

Reading temperature through DHT11 using Android Things

I am using Raspberry pi3 and DHT11 sensor for temperature monitoring project.
I have following pin positions
VCC to pin no : 2
Ground to pin no : 6
Output to GPIO : BCM22 i.e pin no 15
Code that I have used:
public class WeatherStationActivity extends Activity {
private Handler mHandler = new Handler();
private TextView mTxtStatus;
private PeripheralManagerService service = new PeripheralManagerService();
private Gpio tempGpio;
private int i = 0;
int[] dht11_dat = {0, 0, 0, 0, 0};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d("Weather station", "Started Weather Station");
setContentView(R.layout.activity_main);
mTxtStatus = (TextView) findViewById(R.id.txtStatus);
try {
tempGpio = service.openGpio("BCM22");
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
if (i == 10) {
handler.removeCallbacks(this);
} else {
getTemp();
handler.postDelayed(this, 5000);
}
i++;
}
}, 5000);
} catch (Exception e) {
e.printStackTrace();
}
}
private void getTemp() {
boolean laststate = false;
try {
laststate = tempGpio.getValue();
} catch (IOException e) {
e.printStackTrace();
}
int j = 0;
final int MAXTIMINGS = 85;
dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
try {
tempGpio.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW);
// tempGpio.setActiveType(Gpio.ACTIVE_LOW);
tempGpio.setValue(false);
// Thread.sleep(18);
TimeUnit.MILLISECONDS.sleep(18);
// tempGpio.setActiveType(Gpio.ACTIVE_HIGH);
// tempGpio.setActiveType(Gpio.ACTIVE_HIGH);
tempGpio.setValue(true);
TimeUnit.MICROSECONDS.sleep(40);
tempGpio.setDirection(Gpio.DIRECTION_IN);
/* tempGpio.setActiveType(Gpio.ACTIVE_HIGH);
tempGpio.setValue(true);*/
// tempGpio.setValue(true);
StringBuilder value = new StringBuilder();
for (int i = 0; i < MAXTIMINGS; i++) {
int counter = 0;
while (tempGpio.getValue() == laststate) {
counter++;
TimeUnit.MICROSECONDS.sleep(1);
if (counter == 255) {
break;
}
}
laststate = tempGpio.getValue();
mTxtStatus.append("\nLast State of Sensor " + laststate);
if (counter == 255) {
break;
}
//* ignore first 3 transitions *//*
if ((i >= 4) && (i % 2 == 0)) {
//* shove each bit into the storage bytes *//*
dht11_dat[j / 8] <<= 1;
if (counter > 16) {
dht11_dat[j / 8] |= 1;
}
j++;
}
}
// check we read 40 bits (8bit x 5 ) + verify checksum in the last
// byte
if ((j >= 40) && checkParity()) {
value.append(dht11_dat[2]).append(".").append(dht11_dat[3]);
Log.i("Logger", "temperature value readed: " + value.toString());
mTxtStatus.append("\nTemp " + value.toString());
} else {
mTxtStatus.append("\nNothing is working ");
Log.i("Logger", "Nothing is working ");
}
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (Exception ex) {
ex.printStackTrace();
}
}
private boolean checkParity() {
return dht11_dat[4] == (dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3] & 0xFF);
}
}
Above code is giving me "Nothing is working" as output.
Any suggestion where I might be doing wrong?

You can't read data from DHT11 using Raspberry Pi 3 with Android Things because duration of DHT11 response pulses is from 26-28 us to 70 us, but max frequency of RP3 with AT GPIO is around 3kHz, which means around 300 us pulse duration. Take a look at answers to this question.

Android Bluetooth input stream not reading full array

I'm creating an app to read string values over Bluetooth serial port. My data receiving but in two parts. If I send $F00,A,B,0,M# via bluetooth it only reads $ in first part and F00,A,B,0,M# in next part. I provided my code here. Please do correct me if I'm wrong.
InputStream inputStream=null;
int avilableBytes=0;
public ConnectedThread(BluetoothSocket socket){
InputStream temp=null;
try{
temp=socket.getInputStream();
}catch (IOException e){
e.printStackTrace();
}
inputStream=temp;
}
public void run() {
try{
int bytes;
while (true){
try{
avilableBytes=inputStream.available();
if (avilableBytes>0){
byte[] buffer=new byte[avilableBytes];
bytes=inputStream.read(buffer);
final String readMessage=new String(buffer,0,bytes);
bt_handler.obtainMessage(handlerState,bytes,-1,readMessage).sendToTarget();
Log.d("PRAVEEN",readMessage);
}
}catch (IOException e){
e.printStackTrace();
}
}
}catch (Exception e){
e.printStackTrace();
}
}

Data are like stream bytes and can not be processed immediately when it comes with a few bytes. Data will not come all at once as a single packet. You have to use the other byte[] buffer (MainBuffer) in which you will gradually save incoming byte and move the index in that buffer. Then, from time to time (e.g. in the timer once per second) take data from the main buffer and processed it. By default you must implement some data frame with a separator (eg. Data * data * data * - Many ways to do it good or bad). I dealt with this in .net via Xamarin, but just as an example it may be helpfull :
update example, format
In ConnectedThread :
public override void Run()
{
while (true)
{
try
{
int readBytes = 0;
lock (InternaldataReadLock)
{
readBytes = clientSocketInStream.Read(InternaldataRead, 0, InternaldataRead.Length);
Array.Copy(InternaldataRead, TempdataRead, readBytes);
}
if (readBytes > 0)
{
lock (dataReadLock)
{
dataRead = new byte[readBytes];
for (int i = 0; i < readBytes; i++)
{
dataRead[i] = TempdataRead[i];
}
}
Bundle dataBundle = new Bundle();
dataBundle.PutByteArray("Data", dataRead);
Message message = btlManager.sourceHandler.ObtainMessage();
message.What = 1;
message.Data = dataBundle;
btlManager.sourceHandler.SendMessage(message);
}
}
catch (System.Exception e)
{
btlManager.btlState = BTLService.BTLState.Nothing;
}
}
}
In BTLHandler :
public override void HandleMessage(Message msg)
{
switch (msg.What)
{
case 1:
{
byte[] data = msg.Data != null ? msg.Data.GetByteArray("Data") : new byte[0];
btlService.BTLReceiveData(data);
}
break;
}
}
public void BTLReceiveData(byte[] data)
{
lock (dataReadLock)
{
for (int i = 0; i < data.Length; i++)
{
dataRead[dataReadWriteCursor] = data[i];
dataReadWriteCursor++;
}
}
}
In Timer :
int tmpWriteCursor = dataReadWriteCursor;
int tmpReadCursor = dataReadReadCursor;
lock (dataReadLock)
{
int newBytes = dataReadWriteCursor - dataReadReadCursor;
for (int i = 0; i < newBytes; i++)
{
dataReadMain[dataReadReadCursor] = dataRead[dataReadReadCursor++];
}
}
bool odradkovani = false;
string tmpRadek = "";
int lastLineIndex = 0;
List<string> list = new List<string>();
for (int i = LastWriteLineIndex; i < tmpWriteCursor; i++)
{
if (dataReadMain[i] >= 32 && dataReadMain[i] <= 255)
{
tmpRadek += (char)dataReadMain[i];
}
else if (dataReadMain[i] == 13) odradkovani = true;
else if (dataReadMain[i] == 10)
{
if (odradkovani)
{
odradkovani = false;
list.Add(Utils.GetFormatedDateTime(DateTime.Now) + " " + tmpRadek);
tmpRadek = "";
lastLineIndex = i + 1;
}
}
else
{
tmpRadek += "?" + dataReadMain[i].ToString() + "?";
}
}
WriteDataToLog(list);
LastWriteLineIndex = lastLineIndex;

How to write “0xFF” as a characteristics value in android BLE?

I am trying to write hex value 0xFF in the fragrance dispenser device using BluetoothGattCharacteristic method setValue(..) .I do get success status code 0 in the call back method onCharacteristicWrite() But device does not perform any action, ideally it should emit fragrance.
below is my sample code to write to the characteristics
private void writeCharacteristic(CallbackContext callbackContext, UUID serviceUUID, UUID characteristicUUID, byte[] data, int writeType) {
boolean success = false;
if (gatt == null) {
callbackContext.error("BluetoothGatt is null");
return;
}
BluetoothGattService service = gatt.getService(serviceUUID);
BluetoothGattCharacteristic characteristic = findWritableCharacteristic(service, characteristicUUID, writeType);
if (characteristic == null) {
callbackContext.error("Characteristic " + characteristicUUID + " not found.");
} else {
int data2=0xFF;
characteristic.setValue(data2, BluetoothGattCharacteristic.FORMAT_UINT16, 0);
characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
writeCallback = callbackContext;
if (gatt.writeCharacteristic(characteristic)) {
success = true;
System.out.println(" writeCharacteristic success");
} else {
writeCallback = null;
callbackContext.error("Write failed");
}
}
Please suggest way to write hex data in setValue() method of BluetoothGattCharacteristic .
Thanks

0xFF in
BluetoothGattCharacteristic.FORMAT_UINT16 means you'll send FF 00 because you set it to send a 16 bit unsigned number. To send only 0xFF (and I don't know if that makes a difference) you'll have to set the format to UINT8.
characteristic.setValue(data2, BluetoothGattCharacteristic.FORMAT_UINT8, 0);

You can send byte array to charcteristics.
Convert your hex to byte array using below method.link
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
convert your number to hex first ...
public static String toHex(String arg)
{
try
{
return String.format("%01x", new BigInteger(1, arg.getBytes("UTF-8")));
}
catch (UnsupportedEncodingException e)
{
e.printStackTrace();
return "";
}
}
//set data
characteristic.setValue(hexStringToByteArray(toHex(255+""));