The BLE Device Disconnection not working on UWP C#

Manickavasagam C 0

Hello folks,
I'm developing a UWP Application using a C# for establishing the connection between BLE devices like Connect, Read, Write, and Disconnect for that we using a "Windows.Devices.Bluetooth".

I'd successfully completed a few operations like connect, Read, and Write. But when I'm trying to disconnect that connected BLE Device, It does not disconnect the device properly, It takes more than 1.5 - 2 mins. Yeah, I had unsubscribed the notification so the data that we are receiving from the BLE Device was stopped. So, that is not a problem.

The only issue should be that the device not disconnecting from the system.
For Example:
connected_device.Dispose();

If anyone has a solution for this issue, please help me.
Thanks in advance!

Junjie Zhu - MSFT 17,226 Reputation points Microsoft Vendor

2023-09-04T02:39:24.01+00:00

Hi @Manickavasagam C ,

Welcome to Microsoft Q&A!

Have you checked the GattSessionStatus? According to this document Bluetooth GATT Client , you should make sure that there is no other app on the system has a reference to the device.

Thank you.

Manickavasagam C 0

Hello @Junjie Zhu - MSFT

Thanks for your time and response

Let me share, How I'm done a connection and disconnecting the device

Connect To Device

  public static async Task<bool> ConnectToDevice(string lastSixId)
        {
            try
            {
                BluetoothLEDevice previous_connected_device = LocalStorage.GetData_BLE_Device(Constants.DEFAULT_CONNECTED_BLE_DEVICE_SESSION_KEY_NAME);

                //await Logger.AddLog(LogLevel.Info, $"Previous Connected device Address: {previous_connected_device.BluetoothAddress.ToString()}");
                if (previous_connected_device != null && previous_connected_device.ConnectionStatus == BluetoothConnectionStatus.Connected)
                {
                    if (characteristic != null)
                    {
                        characteristic.ValueChanged -= Characteristic_ValueChanged;
                        previous_connected_device.ConnectionStatusChanged -= ConnectedDevice_ConnectionStatusChanged;

                        bool UnSubcribed = await UnsubscribeFromNotificationsAsync(previous_connected_device, serviceUuid, characteristicUuid);

                        if (UnSubcribed)
                        {
                            await Logger.AddLog(LogLevel.Info, $"Attempting to disconnect from Device: {previous_connected_device.Name}  -----  Current Connection Status: {previous_connected_device.ConnectionStatus}");
                            

                            DisconnectDeviceAsync(previous_connected_device);
                            // Assuming the Dispose method should handle the disconnection
                            //previous_connected_device.Dispose();
                            //bool isDisconnected = await DisconnectBLEDevice(previous_connected_device);
                            //await Logger.AddLog(LogLevel.Info, "BLE Device Disconnected: " + isDisconnected);

                            // Increase the delay to ensure the device has enough time to update its status
                            await Task.Delay(5000);

                            await Logger.AddLog(LogLevel.Info, $"Status after attempting disconnection, Device Name: {previous_connected_device.Name}  -----  Connection Status: {previous_connected_device.ConnectionStatus}");

                            Constants.DEVICE_SETTING_PREVIOUS_CONNECTED_DEVICE_NAME = previous_connected_device.Name;
                            StatusManagement(Constants.STATE_PREVIOUS_DEVICE_DISCONNECTED);
                            // If the device is still connected after Disconnect, log an error or handle accordingly
                            //if (previous_connected_device.ConnectionStatus == BluetoothConnectionStatus.Connected)
                            //{
                            //    Constants.DEVICE_SETTING_PREVIOUS_CONNECTED_DEVICE_NAME = previous_connected_device.Name;

                            //    previous_connected_device.Dispose();
                            //    StatusManagement(Constants.STATE_PREVIOUS_DEVICE_DISCONNECTED);
                            //}
                            previous_connected_device = null;
                            LocalStorage.Store_BluetoothLEDevice(Constants.DEFAULT_CONNECTED_BLE_DEVICE_SESSION_KEY_NAME, null);
                            LocalStorage.Store_String(Constants.SAVED_DEVICE_SESSION_KEY_NAME, "");

                            characteristic = null;
                        }
                        else
                        {
                            await Logger.AddLog(LogLevel.Error, "Unsubscribed to notifications was failed");
                        }
                    }
                    else
                    {
                        await Logger.AddLog(LogLevel.Error, "characteristic is null for the previous connected device");
                    }
                }

                var bluetoothAddress = ulong.Parse(lastSixId.Replace(":", ""), System.Globalization.NumberStyles.HexNumber);

                await Logger.AddLog(LogLevel.Info, $"Bluetooth Address: {bluetoothAddress.ToString()}");

                BluetoothLEDevice connectedDevice = await BluetoothLEDevice.FromBluetoothAddressAsync(bluetoothAddress);
                if (connectedDevice != null)
                {
                    bool IsSubscribed = await SubscribeToNotificationsAsync(connectedDevice, serviceUuid, characteristicUuid);

                    if (IsSubscribed)
                    {
                        bool IsStarted = await StartDataReceiveTask(connectedDevice);
                        if (IsStarted)
                        {
                            LocalStorage.Store_String(Constants.SAVED_DEVICE_SESSION_KEY_NAME, lastSixId);
                            LocalStorage.Store_BluetoothLEDevice(Constants.DEFAULT_CONNECTED_BLE_DEVICE_SESSION_KEY_NAME, connectedDevice);

                            Constants.CURRENT_CONNECTED_DEVICE = connectedDevice;
                            StatusManagement(Constants.STATE_CONNECTED);

                            return true;
                        }
                        else
                        {
                            await Logger.AddLog(LogLevel.Info, $"NOT STARTED!");
                        }
                    }
                    else
                    {
                        await Logger.AddLog(LogLevel.Info, $"NOT SUBCRIBED");
                    }
                }
                else
                {
                    await Logger.AddLog(LogLevel.Info, "BluetoothLEDevice is null");
                }
            }
            catch (Exception ex)
            {
                await Logger.AddLog(LogLevel.Info, $"Error on Connect_To_Devices: {ex.ToString()}");
            }
            return false;
        }

Yes, From the above method which I'm sharing, I have checked if Is there any previously connected device, If yes, I'm trying to disconnect and connect to a new BLE Device by using a below line

 BluetoothLEDevice connectedDevice = await BluetoothLEDevice.FromBluetoothAddressAsync(bluetoothAddress);

Here is the method for disconnection

 private static async Task<bool> DisconnectDeviceAsync(BluetoothLEDevice device)
        {
            bool success = true;

            try
            {
                var servicesResult = await device.GetGattServicesAsync();
                if (servicesResult.Status == GattCommunicationStatus.Success)
                {
                    foreach (var service in servicesResult.Services)
                    {
                        service.Dispose();
                    }
                }

                //device = null;
            }
            catch (Exception ex)
            {
                await Logger.AddLog(LogLevel.Error, $"Expection while disconnect the device: {ex}");
                success = false;
            }

These are code which I have used before.

Junjie Zhu - MSFT 17,226 Reputation points Microsoft Vendor

2023-09-04T08:06:37.9266667+00:00

Can this official sample help you? It uses GattClientCharacteristicConfigurationDescriptorValue.None to clear the CCCD.

Manickavasagam C 0

I will try that GattClientCharacteristicConfigurationDescriptorValue.None

        private async Task<bool> DisconnectDevice(BluetoothLEDevice device)
        {
            if (characteristic != null)
            {
                var result = await characteristic.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue.None);
                if (result != GattCommunicationStatus.Success)
                {
                    return false;
                }
                else
                {
                    characteristic.ValueChanged -= Characteristic_ValueChanged;
                }
            }
            device?.Dispose();
            int n = 0;
            while (device.ConnectionStatus != BluetoothConnectionStatus.Disconnected)
            {
                await Task.Delay(1000); // Wait for the device to disconnect
                Debug.WriteLine($"Checking Disconnection Status!, Delay Seconds: {n}");
                n++;
            }
            device = null;
            return true;
        }

It more than a 4min, Still the device not disconnecting from the system.

Junjie Zhu - MSFT 17,226 Reputation points Microsoft Vendor

2023-09-04T09:58:49.5966667+00:00

Can this behavior be reproduced on other devices?
Manickavasagam C 0 Reputation points

2023-09-04T10:16:49.75+00:00

Yes, I'm Developing a UWP Application. When I'm trying to new device, I want to disconnect the previous connected device. At times, When I use the device.Dispose(); The device is not disconnected from the system( When I check with my windows Bluetooth, it shows Connected(1));
Junjie Zhu - MSFT 17,226 Reputation points Microsoft Vendor

2023-09-05T08:50:18.5933333+00:00

How about setting bluetoothLeDevice = null directly after Dispose() like the official sample?
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Roy Li - MSFT 32,921 Reputation points Microsoft Vendor

2023-09-15T01:39:21.7266667+00:00

Any updates about this issue? Have checked Junjie Zhu's suggestion?

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The BLE Device Disconnection not working on UWP C#

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