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Reading Battery info gives strange results

traceyttraceyt
edited February 2017 in C++
I am just getting started building my application.  I decided to try something simple like reading the battery information.  I am using the UWP starter template along with the WinRT C++ API.  I am able to subscribe and read the battery information but the values that I get back are suspect.  In particular the voltage values seem to keep going up and then will all of a sudden reset and then go up again.  I must be doing something wrong here but cannot figure out what else to do.  I have the following code.




        protected override void OnNavigatedTo(NavigationEventArgs e) {
            base.OnNavigatedTo(e);

            BluetoothLEDevice selectedDevice = e.Parameter as BluetoothLEDevice;

            // get the selected device and load into MetawareBoard Model
            MetaWearBoard mwBoard= MetaWearBoard.getMetaWearBoardInstance(selectedDevice);
            cppBoard = mwBoard.cppBoard;

            // subscribe to battery info
            // getting battery signal from the selected board
            batterySignal = mbl_mw_settings_get_battery_state_data_signal(cppBoard);

            // subscribe to receive battery info
            mbl_mw_datasignal_subscribe(batterySignal, new Fn_IntPtr(sensorData =>
            {
                bstate = Marshal.PtrToStructure<batterystate>(sensorData);
                System.Diagnostics.Debug.WriteLine("Battery data: voltage {0}, charge{1}", bstate.voltage.ToString(), bstate.charge.ToString());
            }));

            // this is a inifinite test loop to see whether the values recieved "settle" down.  currently voltage keeps increasing.
            while (true)
            {
                mbl_mw_datasignal_read(batterySignal);
                System.Threading.Tasks.Task.Delay(500).Wait(); 
            }
Here is the data that I am getting back...,
Battery data: voltage 58685, charge67
Battery data: voltage 59165, charge67
Battery data: voltage 59705, charge67
Battery data: voltage 60185, charge67
Battery data: voltage 60665, charge67
Battery data: voltage 61205, charge67
Battery data: voltage 61685, charge67
Battery data: voltage 62165, charge67
Battery data: voltage 62705, charge67
Battery data: voltage 63185, charge67
Battery data: voltage 63725, charge67
Battery data: voltage 64205, charge67
Battery data: voltage 64685, charge67
Battery data: voltage 65226, charge67
Battery data: voltage 170, charge68
Battery data: voltage 649, charge68
Battery data: voltage 1189, charge68
Battery data: voltage 1670, charge68
Battery data: voltage 2150, charge68
Battery data: voltage 2689, charge68
Battery data: voltage 3170, charge68
Battery data: voltage 3649, charge68
Battery data: voltage 4189, charge68
Battery data: voltage 4670, charge68
Battery data: voltage 5210, charge68
Battery data: voltage 5690, charge68
Battery data: voltage 6170, charge68
Battery data: voltage 6710, charge68
Battery data: voltage 7190, charge68
Battery data: voltage 7669, charge68
Battery data: voltage 8210, charge68
Battery data: voltage 8690, charge68
Battery data: voltage 9170, charge68
Battery data: voltage 9710, charge68
Battery data: voltage 10190, charge68
Battery data: voltage 10670, charge68
Battery data: voltage 11210, charge68
Battery data: voltage 11690, charge68
Battery data: voltage 12230, charge68
Battery data: voltage 12770, charge68
Battery data: voltage 13190, charge68
Battery data: voltage 13730, charge68
Battery data: voltage 14210, charge68
Battery data: voltage 14690, charge68
Battery data: voltage 15230, charge68
Battery data: voltage 15710, charge68
Battery data: voltage 16190, charge68
Battery data: voltage 16730, charge68
Battery data: voltage 17210, charge68

Comments

  • EricEric
    edited February 2017
    What board are you using and what firmware version is it running?  Does the same behavior occur if you using an Android or iOS app?
  • traceyttraceyt
    Meta Motion R – 10 Axis IMU + Sensor Fusion is the board
    FW is 1.3.3
    FWIW I was getting the same results even when I was manually making a query about every 20 seconds.
  • traceyttraceyt
    I can run the test Android and/or IOS app. When I choose to read the battery in the IOS app I get a value of 99. It seems like I always get a value from 91 to 99. What exactly is this value telling me?
  • EricEric
    edited February 2017
    The apps report the battery charge value.


    I spotted the issue with the sample code you provided. The the sensorData parameter is a pointer to the Data structure not the sensor's value. It needs to be marshalled to the Data struct first, then the value parameter is marshalled to the battery state struct.

    private Fn_IntPtr dataHandler = new Fn_IntPtr(pointer => { var data = Marshal.PtrToStructure<data>(pointer); System.Diagnostics.Debug.WriteLine(Marshal.PtrToStructure<batterystate>(data.value)); });

    You should also keep a reference to the delegate otherwise it may be garbage collected.
  • traceyttraceyt
    Thanks. I will give this a try.
  • traceyttraceyt
    Fixed my problem. Thanks for the help!
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