如何从 Xamarin.Forms 中的 UWP 访问 PCL 中的参数

Question

I am working with the Xamarin Forms in combination with the I2C devices and the Raspberry Pi. I programmed in C# and the Raspberry Pi was installed with Windows IoT. And I have encountered a problem about the parameter access.

I have a microtimer in the UWP project and I want to read the data from the analog input every 100ms. In the OnTimedEvent, there is a caculation which requires the some parameters which are set in the PCL project,the namespace is "I2CADDA.MainPage.xaml.cs". I tried to set these parameters as public static.

public static double gainFactor = 1;
public static double gainVD = 1;

And in the UWP project , I use the dependency service because I have to use the micro timer, so the realization of the interface is done in "I2CADDA.UWP.MainPage.xaml.cs", in the function OnTimedEvent, I tried to get the parameters from PCL project file.

public void OnTimedEvent(object sender, MicroLibrary.MicroTimerEventArgs timerEventArgs)
        {

            byte[] readBuf = new byte[2];
            I2CDevice.ReadI2C(chan, readBuf); //read voltage data from analog to digital converter
            sbyte high = (sbyte)readBuf[0];
            int mvolt = high * 16 + readBuf[1] / 16;
            val = mvolt / 204.7 + inputOffset;
            val = val / gainFactor / gainVD; //gainFactor and gainVD shows not exist in current context

        }

It seems that the UWP project can not have access to the PCL project in normal way. May I ask how can I solve this problem? Thank you very much!!!

Answer 1

In C#, to call a static Field, you should use the class name to call it,

In your code, the static Fields are in the I2CADDA.MainPage.xaml.cs, and for instance, they are in the I2CADDA.MainPage class, you can call the field as

double Factor = I2CADDA.MainPage.gainFactor;
double VD = I2CADDA.MainPage.gainVD;

So your above code should be like this:

public void OnTimedEvent(object sender, MicroLibrary.MicroTimerEventArgs timerEventArgs)
{

    byte[] readBuf = new byte[2];
    I2CDevice.ReadI2C(chan, readBuf); //read voltage data from analog to digital converter
    sbyte high = (sbyte)readBuf[0];
    int mvolt = high * 16 + readBuf[1] / 16;
    val = mvolt / 204.7 + inputOffset;
    val = val / I2CADDA.MainPage.gainFactor / I2CADDA.MainPage.gainVD; 
}

Please also make sure you have reference the PCL in your UWP project.