How to send more than 20 bytes data over ble in android?

Question

I am trying to send more than 33 bytes using simple loops, Is anybody has idea how to send more than 20 bytes data over android ble.

if(!mConnected) return;
         


        

Answer 1

Instead of using sleep for every chunk, i just found a better and efficient way for my application to send more than 20 bit data.

The packets will be send after onCharacteristicWrite() triggered. i just found out this method will be triggered automatically after peripheral device (BluetoothGattServer) sends a sendResponse() method.

firstly we have to transform the packet data into chunk with this function:

public void sendData(byte [] data){
    int chunksize = 20; //20 byte chunk
    packetSize = (int) Math.ceil( data.length / (double)chunksize); //make this variable public so we can access it on the other function

    //this is use as header, so peripheral device know ho much packet will be received.
    characteristicData.setValue(packetSize.toString().getBytes());
    mGatt.writeCharacteristic(characteristicData);
    mGatt.executeReliableWrite();

    packets = new byte[packetSize][chunksize];
    packetInteration =0;
    Integer start = 0;
    for(int i = 0; i < packets.length; i++) {
        int end = start+chunksize;
        if(end>data.length){end = data.length;}
        packets[i] = Arrays.copyOfRange(data,start, end);
        start += chunksize;
    }

after our data ready, so i put my iteration on this function:

@Override
    public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
        if(packetInteration