2626import android .bluetooth .BluetoothGattCharacteristic ;
2727import android .bluetooth .BluetoothGattService ;
2828import android .content .Context ;
29+ import android .text .TextUtils ;
2930
31+ import java .io .UnsupportedEncodingException ;
3032import java .util .LinkedList ;
3133import java .util .Queue ;
3234import java .util .UUID ;
3638public class UARTManager extends BleManager <UARTManagerCallbacks > {
3739 /** Nordic UART Service UUID */
3840 private final static UUID UART_SERVICE_UUID = UUID .fromString ("6E400001-B5A3-F393-E0A9-E50E24DCCA9E" );
39- /** TX characteristic UUID */
40- private final static UUID UART_TX_CHARACTERISTIC_UUID = UUID .fromString ("6E400002-B5A3-F393-E0A9-E50E24DCCA9E" );
4141 /** RX characteristic UUID */
42- private final static UUID UART_RX_CHARACTERISTIC_UUID = UUID .fromString ("6E400003-B5A3-F393-E0A9-E50E24DCCA9E" );
42+ private final static UUID UART_RX_CHARACTERISTIC_UUID = UUID .fromString ("6E400002-B5A3-F393-E0A9-E50E24DCCA9E" );
43+ /** TX characteristic UUID */
44+ private final static UUID UART_TX_CHARACTERISTIC_UUID = UUID .fromString ("6E400003-B5A3-F393-E0A9-E50E24DCCA9E" );
45+ /** The maximum packet size is 20 bytes. */
46+ private static final int MAX_PACKET_SIZE = 20 ;
4347
44- private BluetoothGattCharacteristic mTXCharacteristic , mRXCharacteristic ;
48+ private BluetoothGattCharacteristic mRXCharacteristic , mTXCharacteristic ;
49+ private byte [] mOutgoingBuffer ;
50+ private int mBufferOffset ;
4551
4652 public UARTManager (final Context context ) {
4753 super (context );
@@ -60,30 +66,59 @@ protected BleManagerGattCallback getGattCallback() {
6066 @ Override
6167 protected Queue <Request > initGatt (final BluetoothGatt gatt ) {
6268 final LinkedList <Request > requests = new LinkedList <>();
63- requests .push (Request .newEnableNotificationsRequest (mRXCharacteristic ));
69+ requests .push (Request .newEnableNotificationsRequest (mTXCharacteristic ));
6470 return requests ;
6571 }
6672
6773 @ Override
6874 public boolean isRequiredServiceSupported (final BluetoothGatt gatt ) {
6975 final BluetoothGattService service = gatt .getService (UART_SERVICE_UUID );
7076 if (service != null ) {
71- mTXCharacteristic = service .getCharacteristic (UART_TX_CHARACTERISTIC_UUID );
7277 mRXCharacteristic = service .getCharacteristic (UART_RX_CHARACTERISTIC_UUID );
78+ mTXCharacteristic = service .getCharacteristic (UART_TX_CHARACTERISTIC_UUID );
79+ }
80+
81+ boolean writeRequest = false ;
82+ boolean writeCommand = false ;
83+ if (mRXCharacteristic != null ) {
84+ final int rxProperties = mRXCharacteristic .getProperties ();
85+ writeRequest = (rxProperties & BluetoothGattCharacteristic .PROPERTY_WRITE ) > 0 ;
86+ writeCommand = (rxProperties & BluetoothGattCharacteristic .PROPERTY_WRITE_NO_RESPONSE ) > 0 ;
87+
88+ // Set the WRITE REQUEST type when the characteristic supports it. This will allow to send long write (also if the characteristic support it).
89+ // In case there is no WRITE REQUEST property, this manager will divide texts longer then 20 bytes into up to 20 bytes chunks.
90+ if (writeRequest )
91+ mRXCharacteristic .setWriteType (BluetoothGattCharacteristic .WRITE_TYPE_DEFAULT );
7392 }
74- return mTXCharacteristic != null && mRXCharacteristic != null ;
93+
94+ return mRXCharacteristic != null && mTXCharacteristic != null && (writeRequest || writeCommand );
7595 }
7696
7797 @ Override
7898 protected void onDeviceDisconnected () {
79- mTXCharacteristic = null ;
8099 mRXCharacteristic = null ;
100+ mTXCharacteristic = null ;
81101 }
82102
83103 @ Override
84104 public void onCharacteristicWrite (final BluetoothGatt gatt , final BluetoothGattCharacteristic characteristic ) {
85- final String data = characteristic .getStringValue (0 );
86- mCallbacks .onDataSent (data );
105+ // When the whole buffer has been sent
106+ final byte [] buffer = mOutgoingBuffer ;
107+ if (mBufferOffset == buffer .length ) {
108+ try {
109+ mCallbacks .onDataSent (new String (buffer , "UTF-8" ));
110+ } catch (final UnsupportedEncodingException e ) {
111+ // do nothing
112+ }
113+ mOutgoingBuffer = null ;
114+ } else { // Otherwise...
115+ final int length = Math .min (buffer .length - mBufferOffset , MAX_PACKET_SIZE );
116+ final byte [] data = new byte [length ]; // We send at most 20 bytes
117+ System .arraycopy (buffer , mBufferOffset , data , 0 , length );
118+ mBufferOffset += length ;
119+ mRXCharacteristic .setValue (data );
120+ writeCharacteristic (mRXCharacteristic );
121+ }
87122 }
88123
89124 @ Override
@@ -100,13 +135,30 @@ protected boolean shouldAutoConnect() {
100135 }
101136
102137 /**
103- * Sends the given text to TH characteristic.
138+ * Sends the given text to RX characteristic.
104139 * @param text the text to be sent
105140 */
106141 public void send (final String text ) {
107- if (mTXCharacteristic != null ) {
108- mTXCharacteristic .setValue (text );
109- writeCharacteristic (mTXCharacteristic );
142+ // An outgoing buffer may not be null if there is already another packet being sent. We do nothing in this case.
143+ if (!TextUtils .isEmpty (text ) && mOutgoingBuffer == null ) {
144+ final byte [] buffer = mOutgoingBuffer = text .getBytes ();
145+ mBufferOffset = 0 ;
146+
147+ // Depending on whether the characteristic has the WRITE REQUEST property or not, we will either send it as it is (hoping the long write is implemented),
148+ // or divide it into up to 20 bytes chunks and send them one by one.
149+ final boolean writeRequest = (mRXCharacteristic .getProperties () & BluetoothGattCharacteristic .PROPERTY_WRITE ) > 0 ;
150+
151+ if (!writeRequest ) { // no WRITE REQUEST property
152+ final int length = Math .min (buffer .length , MAX_PACKET_SIZE );
153+ final byte [] data = new byte [length ]; // We send at most 20 bytes
154+ System .arraycopy (buffer , 0 , data , 0 , length );
155+ mBufferOffset += length ;
156+ mRXCharacteristic .setValue (data );
157+ } else { // there is WRITE REQUEST property
158+ mRXCharacteristic .setValue (buffer );
159+ mBufferOffset = buffer .length ;
160+ }
161+ writeCharacteristic (mRXCharacteristic );
110162 }
111163 }
112164}
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