如何为 BLE 设备设置 RequestPreferredConnectionParameters ThroughputOptimized 属性？

Question

C++, WinRT, VS2017, Win10

I am connecting to a Bluetooth LE Device that will respond with an electrical shock when the command is sent. I notice, however, that there is about a 1 second delay from the time the command is written to the Tx characteristic and the time the electrical shock is actually felt.

At first I was thinking that the connection was being dropped between writes and that the delay was possibly the need for a new connection to be established before the write could take place. But, IF the ConnectionStatus() is actually correct, the device is staying connected.

So, I see that in the BluetoothLEDevice class there is a RequestPreferredConnectionParameters() method. I have already created a BluetoothLEDevice object (device) and I would think that this would come up in Intellisense but the closest thing that comes up is device.RequestAccessAsync .

The docs for RequestPreferredConnectionParameters say that there is a ThroughputOptimized property that"

gets a more aggressive set of connection parameters, optimized for faster throughput at the expense of power usage.

That SOUNDS like it would speed up my connection and write speeds. But how do I do that.

Does anyone know how to set this property for a BLE device or even if I am barking up the wrong tree?

Answer 1

The answer is that I failed to drill down and read the details of BluetoothLEDevice.RequestPreferredConnectionParameters . I see now that it applies to WinRT Build 22000, Build 22621. In my case I am using NuGet 2017 which has an older version of WinRT. I'm assuming that NuGet is the way that WinRT is updated.

When I try to update to the more recent NuGet 2.0.22xx I get the traditional 2613 compile errors which may or may not be caused by only one or two problems. At least this has been my sad experience.

I see that one of the thousands of errors is the this co_await expression requires a suitable "await_ready" function even though it is being used inside of a winrt::Windows::Foundation::IAsyncAction function. In trying to track down this one error I have used the recommended namespaces and included the recommended header files but all of that just got me deeper into the swamp. I have also tried the fire_and_forget return type but the error remains.

For now I'm going back to NuGet 2017. I am trying to keep to VS2017 for now because my main app is fairly large and uses several 3rd party libraries that would all have to be recompiled. My experience is that when porting to a new VS the gremlins come out of the woodwork and it takes time to squash them all. I was hoping not to have to do that until I have more free time.

Any suggestions about using NuGet 2.0.22xxx in a VS2017 MFC app would be appreciated.