Notifications stops when using internal bluetooth

[PauDC]

Hello,

I've asked this question already at StackOverflow, and while I try Wireshark I wanted to see if someone has experienced the same issue and/or can provide further information. Thestack overflow link is the following: Link. The explanation of the issue will be pretty much the same.

I'm developing an UWP app meant for Windows10 that prints connects to the sensor and prints some of the data it sends. It doesn't do anything else.

I have a BLE sensor based on the Nordic nRF52832 SoC that sends data at a frequency of 100Hz and I've developed an UWP application to receive this data. I'm having a weird issue where after a couple of seconds of everything working fine, I stop recieving notifications for new data and the sensor disconnects.

Now, I say it's weird because this happens when I'm using the laptop's internal bluetooth but not when using a bluetooth dongle. When using the dongle it works fine and never stops. Both internal bluetooth and dongle drivers are updated to the latest version Windows can find.

A bit of information about my code:

• I have a Sensor.cs class in which I handle the connection and the streaming of the data.
• I'm using BluetoothLEAdvertisementWatcher in order to find the sensor.
• The GattCharacteristic's are private members of the Sensor class.
• I subscribe to notifications by calling:

  await _gattDataSensorsCharacteristic.WriteClientCharacteristicConfigurationDescriptorAsync(
     GattClientCharacteristicConfigurationDescriptorValue.Notify);

  
  
  
  
• The characteristic I'm calling admits read/notify. And the issue is that characteristic.ValueChanged += Characteristic_ValueChanged; stops firing.

I've done quite a research and couldn't find anything similar. I've found posts about notifications stopping because the object was taken away by the GC, the characteristics were local variables instead of class members or calls weren't awaited.

Things I've tried:

The laptop is running the max performance power consumption profile, this issue happens when the laptop is plugged to a power source or not.

In Windows Device Manager under Bluetooth device properties. Right clicked and checked the propeties of the BT, in the  Power Management tab "Allow the computer to turn off this device to save power" is unchecked.

As posted in StackOverflow, the link to the code I'm using is here: GitHub

Does anybody know why does this happen? Or point me to the right direction to solve the issue? Having to carry the dongle is a pain in the ass and they are rather fragile, I've already broken 2 this month.

Thanks.

1st edit

I've scanned the traffic usig USPCap and loading the data to WireShark. Tried to understand what the pcap file generated by USBPcap, but I simply don't understand. I've tried the issue with 2 sensors and the disconnect/notification stop pattern looks different for each sensor. I've made a Dropbox folder containing the two pcap files: Dropbox

From what I understood, in the file "ble-FE592382586F.pcap" the interesting line No are: 12647 and 12681. It says the source is the controller and the destination is host. Is the controller the laptop's bluetooth driver?

[Hung Bui]

HI PauDC, 

A sniffer trace would be very useful. Just in case you didn't know we provide a sniffer firmware that you can use on the nRF52 DK here. 
Microsoft provided the example here. Does that work for you ? 

[PauDC]

Hi Hung,

I've uploaded the sniffing traces you requested to Dropbox. I'm sorry, I don't have the nRF52DK and I don't think I can get my hand on one due to the quarantine currently going on. I've used USBPcap that sniffs the usb ports on the computer and logs it to a pcap file that easily opens in WireShark. Not sure if that works for you.

And yes, my code is based on that microsoft example.

Thank you.

[Hung Bui]

Hi, 

I couldn't get much information from the log. The device sent notification for about 80 seconds and then it started advertising. 
It could be either the device reset or the connection terminated (doesn't seem like that in the log)

THe sniffer trace would be very useful. 

You can also debug the nRF52 device and check what's the disconnect reason when the BLE_GAP_EVT_DISCONNECTED event occurs. And check if it got a assertion + reset. 

[PauDC]

Hello Hung, the nrf52DK finally arrived and was able to load the sniffer fw. I've updated the dropbox folder in the question with the sniffer trace. File is called 'wiresharklog.pcapng'. My sensor's mac address is DA:DD:55:21:D0:3F.

From the trace, I see that in line 1662 a connection to the sensor is requested, this happens after the sensor disconnects (the issue I'm having). But I can't see when it is disconnecting.

[Hung Bui]

Hi Pau, 

I don't see that the sniffer was following a connection. You would need to select the Device in the sniffer panel on the top before the connection has been made. Then the sniffer can follow the connection.