问题
I'm trying to write a class "Temperature" that handles communicating with my RaspberryPi through SPI to read some temperature data. The goal is to be able to call a GetTemp() method from outside of my Temperature class so that I can use temperature data whenever I need it in the rest of my program.
My code is set up like this:
public sealed class StartupTask : IBackgroundTask
{
private BackgroundTaskDeferral deferral;
public void Run(IBackgroundTaskInstance taskInstance)
{
deferral = taskInstance.GetDeferral();
Temperature t = new Temperature();
//Want to be able to make a call like this throughout the rest of my program to get the temperature data whenever its needed
var data = t.GetTemp();
}
}
Temperature class:
class Temperature
{
private ThreadPoolTimer timer;
private SpiDevice thermocouple;
public byte[] temperatureData = null;
public Temperature()
{
InitSpi();
timer = ThreadPoolTimer.CreatePeriodicTimer(GetThermocoupleData, TimeSpan.FromMilliseconds(1000));
}
//Should return the most recent reading of data to outside of this class
public byte[] GetTemp()
{
return temperatureData;
}
private async void InitSpi()
{
try
{
var settings = new SpiConnectionSettings(0);
settings.ClockFrequency = 5000000;
settings.Mode = SpiMode.Mode0;
string spiAqs = SpiDevice.GetDeviceSelector("SPI0");
var deviceInfo = await DeviceInformation.FindAllAsync(spiAqs);
thermocouple = await SpiDevice.FromIdAsync(deviceInfo[0].Id, settings);
}
catch (Exception ex)
{
throw new Exception("SPI Initialization Failed", ex);
}
}
private void GetThermocoupleData(ThreadPoolTimer timer)
{
byte[] readBuffer = new byte[4];
thermocouple.Read(readBuffer);
temperatureData = readBuffer;
}
}
When I add a breakpoint in GetThermocoupleData(), I can see that I am getting the correct sensor data values. However when I call t.GetTemp() from outside of my class, my value is always null.
Can anyone help me figure out what I'm doing wrong? Thank you.
回答1:
GetThermocouplerData() must have been called atleast once to return data. In your code sample it will not have been run until 1 second after instantiation. Just add a call to GetThermocoupleData(null) in InitSpi in the last line of your try block so that it starts off already having at least 1 call.
来源:https://stackoverflow.com/questions/38038788/getting-spi-temperature-data-from-outside-of-class