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

Sending more than 20 bytes via BLE is easily achievable by splitting your data into 20 byte packets and implementing a short delay (i.e. using sleep()) between sending each packet.

Here's a short snippet of code from a project I'm working on that takes data in the form of byte[] and splits it into an array of the same, ( byte[][] ), in 20 byte chunks, and then sends it to another method that transmits each packet one by one.

    int chunksize = 20;
    byte[][] packets = new byte[packetsToSend][chunksize]; 
    int packetsToSend = (int) Math.ceil( byteCount / chunksize);

    for(int i = 0; i < packets.length; i++) {
        packets[i] = Arrays.copyOfRange(source,start, start + chunksize);
        start += chunksize;
    }

    sendSplitPackets(packets);

Here are two other very good explanations of how to achieve this:

(Stackoverflow) Android: Sending data >20 bytes by BLE

(Nordic Semi) Dealing Large Data Packets Through BLE