AccessViolationException error when retrying InitializeAsync() method

vdacc · October 2018

Hi,
I am currently making console application which I later want to use in Unity3d. I am using the .NetStandard libraries for this.
Sometimes I get the error System.AccessViolationException when retrying the InitializeAsync() method. I have already tried setting the TimeForResponse to 1000 but the error still came back albeit only once in 10 or so tries.

Any help would be appreciated!

Eric · October 2018

What's your retry InitializeAsync code?

vdacc · October 2018

public InitSensor(string mac, string text)
        {
            metaWearBoard = Application.GetMetaWearBoard(mac);
            metaWearBoard.TimeForResponse = 1000;
            Console.WriteLine(Task.CurrentId);
            Task t = Task.Run(metaWearBoard.InitializeAsync);
            Console.WriteLine(t.Id + " " + t.Status);

            while (!t.Status.Equals(TaskStatus.RanToCompletion))
            {
                Task.Delay(1000).Wait();

                Console.WriteLine(t.Id + " " + t.Status);

                if (t.Status.Equals(TaskStatus.Faulted))
                {
                    Task.Delay(1000).Wait();
                    t = Task.Run(metaWearBoard.InitializeAsync);
                }
            }
    }

Can't use await because this is within a class constructor.

Eric · October 2018

You should restructure your code so the constructor isn't calling InitializeAsync.

Do you see the same error if you use async/await, such as in the example code?
https://github.com/mbientlab/MetaWear-SDK-CSharp-Plugin-NetStandard#usage

vdacc · October 2018

This helps with the errors in the console app but when I try to use await the InitializeAsync() in Unity it never returns to the main thread. This causes Unity to just freeze and eventually crash.

Eric · October 2018

What BLE library are you using?

vdacc · November 2018

The Warble.NetStandard one from the MbientLab repositories.
https://github.com/mbientlab/Warble.NET/tree/master/Warble.NetStandard

Eric · November 2018

Sounds like the same issue discussed in this thread:

https://mbientlab.com/community/discussion/2601/unity-works-perfectly-with-metawear-sensor-on-first-run-hangs-on-2nd-run#latest

ebadier · December 2018

Hi Guys,

You could be insterested by these projects:
https://github.com/ebadier/MetaWearRPCServer
https://github.com/ebadier/MetaWearUnityRPC

Best,

AccessViolationException error when retrying InitializeAsync() method

Comments