Android BLE services not discovered

RE: Android BLE services not discovered

Crafter05 — Wed, 16 Oct 2019 17:42:22 GMT

I am having the same issue with my Lenovo Tab 3 Pro, Android 6.1, connecting to Nordic device with Uart service, No matter the Mobile app, or SDK 15.2 package example I run I always connect, start service discovery and timeout.

Your suggestion about the bonding of devices led me to look into the SDK 15.2 for an example with security bonding and I tried the example, nRF5_SDK_15.2.0_9412b96\examples\ble_peripheral\ble_app_gatts_c

It will finally connect to the Lenovo running the nrf Connect app, but it took me a while to notice when the device is connecting, the Lenovo vibrates(default notification alert) and has a pop up notification for pair request.

If you do not click on and accept this pair request, the device will never let the app connect to it.

After clicking accept, services are discovered, everything is running great on the nrf Connect app, and I can disconnect/reconnect without this pair request coming up anymore.

Hope you can find a solution from this example like I will be trying to do next.

RE: Android BLE services not discovered

gaminn — Tue, 08 Oct 2019 10:04:43 GMT

Unfortunately, I don't have spare nrf52 board, I will try to get it. I must correct myself - the error is not related to MTU size, but the fact that pairing is requested from my Qt app (by calling https://doc.qt.io/qt-5/qbluetoothlocaldevice.html#requestPairing). If I bond my device using tablet's bluetooth settings or using nrf Connect, then later in my app I'm able to connect to the device and discover all services. I know the sniffer is neccessary to debug this issue, but maybe someone else had similar issue and can help me.

RE: Android BLE services not discovered

Torsten Robitzki — Tue, 08 Oct 2019 09:36:40 GMT

Both parties negotiate an MTU size that fits both devices. So, this should never be a problem. Hence the suggestion to use a sniffer. If you have any spare nrf52 eval board, you can use it as sniffer and we could then help you. Without that information, it's pure guessing.

RE: Android BLE services not discovered

gaminn — Tue, 08 Oct 2019 09:19:16 GMT

I can confirm, that changing MTU to 23 bytes helps on Lenovo tab E8. But it would be nice to have 247 MTU size. Does it mean there are Android devices that do not support different MTU sizes? Any resources to study this?

RE: Android BLE services not discovered

Torsten Robitzki — Tue, 08 Oct 2019 08:56:01 GMT

If you suspect the MTU size, have you tried a MTU size of 23? You should try to use a sniffer, otherwise it's just guessing.