Retrieving info from multiple sensors using Windows Sensor API - c++

Question

I am using the Windows Sensor API to get info from various sensors including accelerometer and gyroscope. (https://learn.microsoft.com/en-us/windows/desktop/sensorsapi/sensor-api-programming-guide)
My initial implementation of sensor driver for accelerometer worked - I asynchronously can get the values for that sensor.
The working initialization code for a single sensor (accelerometer) looks like the following:
void initialize1(AccelerometerCallBack callBack) {
HRESULT hr = S_OK;
CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
ISensorManager* pSensorManager = NULL;
ISensorCollection* pSensorColl = NULL;
ISensor* accelerometer = NULL;
hr = CoCreateInstance(CLSID_SensorManager,
NULL, CLSCTX_INPROC_SERVER,
IID_PPV_ARGS(&pSensorManager));
if (SUCCEEDED(hr))
{
printf("Succeeded getting Sensor...\n");
ULONG ulCount = 0;
// Verify that the collection contains
// at least one sensor.
hr = pSensorColl->GetCount(&ulCount);
if (SUCCEEDED(hr))
{
if (ulCount < 1)
{
wprintf_s(L"\nNo sensors of the requested category.\n");
hr = E_UNEXPECTED;
}
}
}
else {
printf("Failed to get Sensor...\n");
}
if (SUCCEEDED(hr))
{
// Get the first available sensor.
hr = pSensorColl->GetAt(0, &accelerometer);
BSTR name = 0;
hr = accelerometer->GetFriendlyName(&name);
wprintf(L"%s\n", name);
}
AccelerometerEvent* pEventClass = NULL;
ISensorEvents* pMyEvents = NULL;
if (SUCCEEDED(hr))
{
// Create an instance of the event class.
pEventClass = new(std::nothrow) AccelerometerEvent();
pEventClass->globalCallBack = callBack;
}
if (SUCCEEDED(hr))
{
// Retrieve the pointer to the callback interface.
hr = pEventClass->QueryInterface(IID_PPV_ARGS(&pMyEvents));
}
if (SUCCEEDED(hr))
{
// Start receiving events.
hr = accelerometer->SetEventSink(pMyEvents);
}
MSG msg;
BOOL bRet;
while ((bRet = GetMessage(&msg, NULL, 0, 0)) != 0)
{
if (bRet == -1)
{
// handle the error and possibly exit
}
else
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
}
Now I wanted to simultaneously get the gyroscope, so I add a similar initialization code:
void initialize2(GyroscopeCallBack callBack);, which does similar thing as above.
Now my C# layer triggers those code like this:
internal void Start()
{
AccelerometerCallBack myCallBack1 = new AccelerometerCallBack(onAccelerometerDataChanged);
initialize1(myCallBack1);
GyroscopeCallBack myCallBack2 = new GyroscopeCallBack(onGyroscopeDataChanged);
initialize2(myCallBack2);
}
However, only the accelerometer info is received through the callback, not the gyroscope's.
I have confirmed that my device has both sensors of the correct type
I have confirmed that my callback functions and C# to C++ interface all works properly
What is the correct way to "fetch" multiple sensors (instead of one) using the Windows Sensor API?
There are no examples on the official website about doing this, and the only related SO post (Exposing multiple sensors on a single device to Windows Sensor API) does not help. Thanks!

Answer 1

It worked! Solution was to remove the message pump and use COINIT_MULTITHREADED option for Coinitializine(). Thanks for all the help.