如何解决EventHandler传递连续的异步I2C数据以在ViewModel中使用
我正在使用连接到Raspberry Pi的I2C传感器，并且需要从该总线收集并报告连续数据并将其传递，以便我可以处理数据并使用传感器读数更新GUI。我正在使用.NET Core，以便可以在Linux上跨平台，并且无法在Pi上的Async I2C集合上找到资源。
我目前可以正确地从I2C总线提取数据，并且知道如何实现/更新ViewModel，只是不知道如何在新线程上连续提取数据。
我有使用内置using System.IO.Ports的{{1}}在Windows中进行类似工作的经验，但是由于我从头开始盯着这里，我遇到了一些障碍。这是我第一次深入研究异步任务和事件处理程序，它们本身可能会造成一些混乱。
到目前为止2个主要问题： 如何收集异步或新线程上的I2C数据？ 如何将其传递给不同线程上的同步方法？
下面的代码是我到目前为止所拥有的。
I2CInitialize.cs
DataReceivedEventHandlersMainWindow.cs
public class I2CInitialize
{
public event EventHandler<I2CDataEventArgs> NewI2CDataRecieved;
///Need to call readingi2c in new thread and pass continuous i2c sensor data
public static string readingi2c()
{
int i = 0
while (true)
{
///Taking advantage of using's dispose feature so that memory isn't consumed on loop
using (var i2cBus = new I2CBus(bus))
{
///Driver to get I2C bytes from bus sits here. Returns bytes and converts to string
string result;
result = "I2CDataString";
return result;
}
}
}
///Calls readingi2c() and passes continuous string "data" to subscribers
public void I2C_DataRecieved()
{
string data = readingi2c();
if (NewI2CDataRecieved != null)
NewI2CDataRecieved(this,new I2CDataEventArgs(data));
}
public class I2CDataEventArgs : EventArgs
{
public I2CDataEventArgs(string dataInByteArray)
{
Data = dataInByteArray;
}
public string Data;
}
}
解决方法
我能够采用上述方法，并引用here的建议来避免Thread.Abort。似乎这种方法并不是暂时推荐的终止线程的方法。我当前的方法添加了一个布尔值来结束线程。因为线程必须完全完成而不是立即被终止，所以这是解决此问题的一种备受争议的方法。对于我的应用程序，只需要完成从I2C传感器获取16个字节的过程，该传感器基本上是瞬时的，并且对计算周期和/或最终用户体验没有实际影响。我还使I2Cnitialize成为Singleton，以便可以从应用程序中任何位置的同一实例启动和停止线程。
I2CInitialize.cs
public sealed class I2CInitialize
{
//Start Singleton instance
public static I2CInitialize Instance { get; private set; }
private I2CInitialize() { }
static I2CInitialize() { Instance = new I2CInitialize(); }
public event EventHandler<I2CDataEventArgs> NewI2CDataRecieved;
private Thread i2cThread;
//Set this bool to true or false to run new thread
public bool i2cReadBool;
public void readingi2c()
{
//If bool is true run continuously and send data
while (i2cReadBool)
{
//Keep this using keyword for disposing of continuous data
using (var i2cBus = new I2CBus(bus))
{
//Get data from I2C Bus here
string result;
result = "I2CDataString";
//With the question mark you can omit the if-statement.
EventHandler<I2CDataEventArgs> handler = NewI2CDataRecieved;
handler?.Invoke(this,new I2CDataEventArgs(result));
}
}
}
//Starts the thread
public void I2C_StartReceiveData()
{
if (i2cThread == null || !i2cThread.IsAlive)
{
i2cReadBool = true;
ThreadStart ts = new ThreadStart(() => readingi2c());
i2cThread = new Thread(ts);
i2cThread.Start();
}
}
//Stops the thread
//After adding 'using' reference to this namespace you can call this
//function to stop the thread from anywhere:
//I2CInitialize.Instance.I2C_StopReceiveData();
public void I2C_StopReceiveData()
{
if (i2cReadBool)
{
i2cReadBool = false;
}
}
}
MainWindow.cs
public class MainWindow : Window
{
public void _NewI2CDataRecieved(object sender,I2CDataEventArgs e)
{
string RawStr = e.Data;
//Update UI from RawStr string here
}
public MainWindow()
{
//Call I2CInitialize with Sinleton allows us to call from anywhere
//using I2CInitialize.Instance
I2CInitialize.Instance.NewI2CDataRecieved += _NewI2CDataRecieved;
I2CInitialize.Instance.I2C_StartReceiveData();
}
}
要停止/结束线程，您只需要调用I2CInitialize.Instance.I2C_StopReceiveData();
确保将此添加到应用程序窗口的关闭事件中，以使线程在关闭主应用程序窗口后不会继续运行。
我会这样做：
I2CInitialize.cs
public event EventHandler<I2CDataEventArgs> NewI2CDataRecieved;
private Thread i2cThread;
// changed to public void
public void readingi2c()
{
while (true)
{
using (var i2cBus = new I2CBus(bus))
{
string result;
result = "I2CDataString";
//With the question mark you can omit the if-statement.
EventHandler<I2CDataEventArgs> handler = NewI2CDataRecieved;
handler?.Invoke(this,new I2CDataEventArgs(result));
}
}
}
// Starts the thread
public void I2C_StartReceiveData()
{
if (i2cThread == null || !i2cThread.IsAlive)
{
ThreadStart ts = new ThreadStart(() => readingi2c());
i2cThread = new Thread(ts);
i2cThread.Start();
}
}
// Stops the thread
public void I2C_StopReceiveData()
{
if (i2cThread != null || i2cThread.IsAlive)
{
i2cThread.Abort();
}
}
public class I2CDataEventArgs : EventArgs
{
public I2CDataEventArgs(string dataInByteArray)
{
Data = dataInByteArray;
}
public string Data;
}
然后，您可以在I2C_StartReceiveData()中呼叫MainWindow，例如：
public class MainWindow : Window
{
// Helpful in main class so that we don't have to make a new instance every time we need it
I2CInitialize _i2cInitialize = new I2CInitialize();
public void _NewI2CDataRecieved(object sender,I2CDataEventArgs e)
{
// You must use e.Data and not e.ToSting().
string RawStr = e.Data;
}
public MainWindow()
{
//var _i2cInitialize = new I2CInitialize();
_i2cInitialize.NewI2CDataRecieved += _NewI2CDataRecieved;
_i2cInitialize.I2C_StartReceiveData();
}
}
顺便说一句，您无需指定EventHandler即可注册事件。
要停止线程，可以注册关闭事件并调用I2C_StopReceiveData()。
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