how to enable notification

[matej1410]

 Hello.

I just found here: https://nordicsemiconductor.github.io/Nordic-Thingy52-FW/documentation/firmware_architecture.html

something like this:

"To turn on sensor reading, enable notifications from the desired characteristic by writing 0x0001 to the Client Characteristic Configuration Descriptor (CCCD) for that characteristic."

but I don know how to do that.

Here is my code:

  @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            super.onServicesDiscovered(gatt, status);

           
            UUID SERVICE_UUID=UUID.fromString           ("EF680200-9B35-4933-9B10-52FFA9740042");
            UUID CHARACTERISTIC_UUID=UUID.fromString    ("EF680201-9B35-4933-9B10-52FFA9740042");


            BluetoothGattService service = gatt.getService(SERVICE_UUID);
            BluetoothGattCharacteristic characteristic = service.getCharacteristic(CHARACTERISTIC_UUID);
            gatt.readCharacteristic(characteristic);
            gatt.setCharacteristicNotification(characteristic,true);
            bluetoothLeScanner.stopScan(scanCallback);

        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            super.onCharacteristicRead(gatt, characteristic, status);

           
            byte[] moja_tablica = new byte[3];
            gatt.setCharacteristicNotification(characteristic,true);
            moja_tablica= characteristic.getValue();

        }

How to writie 0x0001 to the Client Characteristic Configuration Descriptor (CCCD) for that characteristic?

[matej1410]

I found this:

BluetoothGattDescriptor descriptor = characteristic.getDescriptor(
        UUID.fromString(SampleGattAttributes.CLIENT_CHARACTERISTIC_CONFIG));
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
bluetoothGatt.writeDescriptor(descriptor);

but I still dont know what is in my case:

SampleGattAttributes.CLIENT_CHARACTERISTIC_CONFIG

and

BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE

 

[matej1410]

  @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            super.onServicesDiscovered(gatt, status);

            

            UUID SERVICE_UUID=UUID.fromString           ("EF680200-9B35-4933-9B10-52FFA9740042");
            UUID CHARACTERISTIC_UUID=UUID.fromString    ("EF680201-9B35-4933-9B10-52FFA9740042");

            BluetoothGattService service = gatt.getService(SERVICE_UUID);
            BluetoothGattCharacteristic characteristic = service.getCharacteristic(CHARACTERISTIC_UUID);

            BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));
            descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
            gatt.writeDescriptor(descriptor);
            bluetoothLeScanner.stopScan(scanCallback);

            gatt.readCharacteristic(characteristic);
            gatt.setCharacteristicNotification(characteristic,true);


        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            super.onCharacteristicRead(gatt, characteristic, status);

        }

        @Override
        public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            super.onCharacteristicWrite(gatt, characteristic, status);
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
            super.onCharacteristicChanged(gatt, characteristic);
            
            //here we read changes for example:
                byte[] moja_tablica = new byte[2];
                moja_tablica= characteristic.getValue();
            
        }

thats all :-)

[ovrebekk]

Hi

Do you mean to say you found the solution?

The last code you sent appears to be correct. 

Best regards
Torbjørn

[matej1410]

Hi. Yes the last is correct. Checked :-)

[ovrebekk]

That's good to hear