我正在尝试创建一个类,用于初始化覆盆子和arduino之间的串行连接。该类还应能够通过已建立的串行连接进行读写。
我使用的代码来自microsoft developers website。
using Windows.Storage.Streams;
using Windows.Devices.Enumeration;
using Windows.Devices.SerialCommunication;
public async void Serial()
{
/* Find the selector string for the serial device */
string aqs = SerialDevice.GetDeviceSelector("UART0");
/* Find the serial device with our selector string */
var dis = await DeviceInformation.FindAllAsync(aqs);
/* Create an serial device with our selected device */
SerialDevice SerialPort = await SerialDevice.FromIdAsync(dis[0].Id);
/* Configure serial settings */
SerialPort.WriteTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.ReadTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.BaudRate = 9600;
SerialPort.Parity = SerialParity.None;
SerialPort.StopBits = SerialStopBitCount.One;
SerialPort.DataBits = 8;
/* Write a string out over serial */
string txBuffer = "Hello Serial";
DataWriter dataWriter = new DataWriter();
dataWriter.WriteString(txBuffer);
uint bytesWritten = await SerialPort.OutputStream.WriteAsync(dataWriter.DetachBuffer());
/* Read data in from the serial port */
const uint maxReadLength = 1024;
DataReader dataReader = new DataReader(SerialPort.InputStream);
uint bytesToRead = await dataReader.LoadAsync(maxReadLength);
string rxBuffer = dataReader.ReadString(bytesToRead);
}
我给Package.appxmanifest添加了串行通信功能。
<Capabilities>
<DeviceCapability Name="serialcommunication">
<Device Id="any">
<Function Type="name:serialPort" />
</Device>
</DeviceCapability>
</Capabilities>
到目前为止,一切都很正常。Raspberry成功地从另一端的Arduino发送和接收消息。
现在,我尝试分别执行这些步骤。首先初始化串行连接,以便在应用程序需要时随时使用读写函数。
MainPage
namespace SerialUART
{
public sealed partial class MainPage : Page
{
private SerialController serial = new SerialController();
public MainPage()
{
this.InitializeComponent();
serial.Write();
serial.Read();
}
}
}
SerialController
using Windows.Devices.Enumeration;
using Windows.Devices.SerialCommunication;
using Windows.Storage.Streams;
namespace SerialUART
{
class SerialController
{
private SerialDevice SerialPort;
private DataWriter dataWriter;
private DataReader dataReader;
public SerialController()
{
InitSerial();
}
private async void InitSerial()
{
string aqs = SerialDevice.GetDeviceSelector("UART0");
var dis = await DeviceInformation.FindAllAsync(aqs);
SerialPort = await SerialDevice.FromIdAsync(dis[0].Id);
// The program does not wait here and executes Write()
// after Write() the following code will be executed
SerialPort.WriteTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.ReadTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.BaudRate = 9600;
SerialPort.Parity = SerialParity.None;
SerialPort.StopBits = SerialStopBitCount.One;
SerialPort.DataBits = 8;
dataWriter = new DataWriter();
dataReader = new DataReader(SerialPort.InputStream);
}
public async void Read()
{
/* Read data in from the serial port */
const uint maxReadLength = 1024;
uint bytesToRead = await dataReader.LoadAsync(maxReadLength);
string rxBuffer = dataReader.ReadString(bytesToRead);
Debug.WriteLine(rxBuffer);
}
public async void Write()
{
/* Write a string out over serial */
string txBuffer = "Hello Serial";
dataWriter.WriteString(txBuffer);
uint bytesWritten = await SerialPort.OutputStream.WriteAsync(dataWriter.DetachBuffer());
}
}
}
此代码不等待serialPort、dataWriter和dataReader初始化。所以他们永远不会被分配到。
有人能给我解释一下为什么它不等待串行连接吗?那该怎么做呢?
发布于 2017-01-16 02:57:25
这是你的构造函数:
public SerialController()
{
InitSerial();
}
它调用InitSerial()
方法,该方法中有几个await。构造函数会立即返回,而不会执行所需的所有操作。然后调用以下方法:
serial.Write();
serial.Read();
但是这些方法依赖于在InitSerial
方法中执行的每一行代码,但显然它们没有。
解决这个问题的一种方法是使InitSerial
不是私有的(内部的或公共的),并让它返回Task
。当你调用它的时候,你需要等待它,这样它才能被执行到完成。然后,您可以调用serial.Write()
和Serial.Read()
。
您应该避免使用async void
。它们仅用于事件处理。对于其他方法,返回Task
或Task<T>
。
https://stackoverflow.com/questions/41664697
复制相似问题