Android BLE read Gatt Characteristic

Question

I am trying to read some Bluetooth Characteristics in my APP. Now i have a Problem with what to do after the characteristic changed from my Gatt Server. At first i've tried to use a thread to retrigger the read for the characteristic again and again like this:

new Thread(new Runnable() {
    @Override
    public void run() {
        int[] newData = new int[30];
        while(true){
            try{
                for(int i=0;i<newData.length;i++){
                    newData[i] = 0;
                }
                BluetoothGatt tmpGatt = refExtDataClass.getRefBluetoothGatt();
                tmpGatt.readCharacteristic(characteristic);

                byte[] value = characteristic.getValue();

                for(int i=0;i<newData.length;i++){
                    newData[i] = value[i];
                }
                refExtDataClass.setNmData(newData);
            }catch(Exception e){
                break;
            }
        }
    }
}).start();

But the Problem is that it's seems like the data is corrupt at one point (like i've always writing the same data into the characteristic from my MCU side).

Is it allowed to read BLE data like this? Is there any suggested way to read BLE data all the time? Or update it on my App side?

If you Need any additional code, please let me know.

score 2 · Answer 1 · answered Sep 28 '16 at 08:30

2

Reading GATT characteristics is an asynchronous operation. The result is not available until you receive the onCharacteristicRead callback.

Anyway, you should rather configure your GATT server to send notifications when it has new data to send rather than polling it all the time.

answered Sep 28 '16 at 08:30

Emil

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good to hear that there is another way i didn't like my "solution" at all. i've just read that i Need to "activate" the notifications from my gatt Client side. is it enough if i am using characteristic.addDescriptor(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE)? – B. Ben Sep 28 '16 at 08:56
No see the example at https://developer.android.com/guide/topics/connectivity/bluetooth-le.html#notification – Emil Sep 28 '16 at 11:46

Android BLE read Gatt Characteristic

1 Answers1