RE: Android scanner app connects to device but my program doesn't

Aleksander Nowakowski — Wed, 16 May 2018 14:48:16 GMT

Hi,

So what I would recommend is:

1. First always connect with autoConnect = false, as it's much faster. Only when the device looses link and the app is in background you may use autoConnect = true so you don't bother with timeouts, etc. But when user awaits actively, use false.

2. Try connecting on UI thread. Some phones, for example from Samsung, like when you do BLE operations on the main thread.

3. If other devices are working, I'd say it's something with the weight scale. Did you try to sniff or get HCI snoop logs from the Android? Did you compare to other devices, is there any difference?

4. Did you try another phone? It may be that your phone does not support some feature and after feature exchange it disconnects instead of ignoring it.

The Android API on Android is so simple, that it's really hard to do it wrong. Unfortunately, there is a lot of 'workarounds' to make a connection more stable, like add delays, use UI thread, retry, clear device cache, etc, but none of then should be required.

PS. I recommend using our BLE Library (https://github.com/NordicSemiconductor/Android-BLE-Library/) for keeping the connection, and in fact version 2 of it (develop branch). Version 2-alpha is highly not-stable but I'd like some feedback! However, RxAndroidBle should also work properly.

RE: Android scanner app connects to device but my program doesn't

Rob Lewis — Thu, 10 May 2018 21:22:53 GMT

Scan first, which finds the device, then

mBluetoothGatt = mBluetoothDevice.connectGatt(mContext, shouldAutoConnect, mGattCallback);

Have tried with shouldAutoConnect both true and false.

Log:

05-07 08:57:09.986 15763-15826/com.calderadev.x200health D/BluetoothGatt: onClientConnectionState() - status=133 clientIf=6 device=88:1B:99:04:D7:40

05-07 08:57:09.986 15763-15826/com.calderadev.x200health D/AbstractBleInteractor: [Callback] Connection state changed with status: 133 and new state: 0 (DISCONNECTED)
05-07 08:57:09.986 15763-15826/com.calderadev.x200health W/AbstractBleInteractor: Error: (0x85)
05-07 08:57:09.987 15763-15826/com.calderadev.x200health D/AbstractBleInteractor: Status's value (decimal) = 133
onConnectionStateChange() - bluetoothGattOpenCount is at 1
05-07 08:57:09.987 15763-15826/com.calderadev.x200health W/AbstractBleInteractor: BluetoothProfile.STATE_DISCONNECTED, closing connections and sending DeviceCommunicationsFailEvent
05-07 08:57:09.987 15763-15826/com.calderadev.x200health D/AbstractBleInteractor: closeConnection()
05-07 08:57:09.988 15763-15826/com.calderadev.x200health D/AbstractBleInteractor: gatt.closeConnection()
05-07 08:57:09.988 15763-15826/com.calderadev.x200health D/BluetoothGatt: close()
05-07 08:57:09.989 15763-15826/com.calderadev.x200health D/BluetoothGatt: unregisterApp() - mClientIf=6
05-07 08:57:09.993 15763-15826/com.calderadev.x200health D/AbstractBleInteractor: closeConnection() - bluetoothGattOpenCount reducing to 0
05-07 08:57:09.993 15763-15826/com.calderadev.x200health D/DefaultDeviceInteractor: onDeviceDisconnected
05-07 08:57:09.995 15763-15763/com.calderadev.x200health D/PairDevicePresenter: onDeviceDisconnected
05-07 08:57:10.000 15763-15763/com.calderadev.x200health D/MainActivity: onDeviceCommunicationsFail

As noted, it works with other devices.