StartUpdatesAsync() / ValueUpdated not called

Hi, The component I want to connect to works as follows: We write in a characteristic (TX) and we come to read the answer in another characteristic (RX).

The RX characteristic has the following attributes: canread: false canwrite: false cannotify: true So I can not do it by simple reading. I tried the following code for an event to be called when the characteristic is changed, but the program never goes into this event.

I have tried many solutions already proposed in the previous discussions but none has worked for now. However I am beginner in xamarin, Maybe I did something wrong.

this.Adapter.DeviceConnected += async (s, a) =>
            {
                Xamarin.Forms.Device.BeginInvokeOnMainThread(new Action(async () =>
                {
                    this.Connected = true;
                    this.Not_Connected = false;
                    this.Liste_Device_Connected.Add(a.Device);

                    this.Service_Selected = await this.Device_Selected.GetServiceAsync(Guid.Parse("6E400001-B5A3-F393-E0A9-E50E24DCCA9E"));
                    this.Characteristic_TX = await this.Service_Selected.GetCharacteristicAsync(Guid.Parse("6e400002-b5a3-f393-e0a9-e50e24dcca9e"));
                    this.Characteristic_RX = await this.Service_Selected.GetCharacteristicAsync(Guid.Parse("6e400003-b5a3-f393-e0a9-e50e24dcca9e"));
                    await Task.Delay(1000);

                    this.Characteristic_RX.ValueUpdated += (o, args) =>
                    {
                        var bytes = args.Characteristic.Value;
                    };
                    await Task.Delay(1000);
                    await this.Characteristic_RX.StartUpdatesAsync();
                    await Task.Delay(1000);

                    byte[] octet = new byte[1];
                    octet[0] = 0x82;
                    var y = await this.Characteristic_TX.WriteAsync(octet);
                }));
                
            };

Expected behavior

it should go into the event just after writing the TX characteristic

Actual behavior

It don’t go into event.

Crashlog

none

Configuration

Version of the Plugin: 1.3.0

Platform: e.g. Android 8.0

Device: Huawei P20 light

[ffrige]

@Joden31 @xabre were you guys able to find what causes this issue? I have the same problem here: I can write and read fine but I cannot get notifications. The code where I call StartUpdatesAsync does not generate any exception, but the ValueUpdated event is never called.

I tried with a 3rd party application on the same Android device and it works fine, so the server is sending out data correctly, I just can’t receive it on my side.

I also tried the suggestion mentioned by @ilakidain but it did not change anything, unfortunately.

What else could it be? Permissions? Timings? Thanks for your help.

[ffrige]

Since no activity or response was given here I decided to switch to another similar Bluetooth package (https://github.com/nexussays/ble.net) and found that it works flawlessly.