因此，我找到了一种使用Windows 10 IoT核心版从UART通道读取串行数据的方法。现在，我得到了一些数据，但是它立即崩溃并返回Exception thrown: 'System.NullReferenceException' in System.Private.CoreLib.ni.dll。
我用来获取数据的代码：
private async Task read_gps_data(string port = "UART0", int baud = 9600)
{
try
{
await Task.Run(async () =>
{
while (true)
{
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
{
string aqs = SerialDevice.GetDeviceSelector("UART0"); /* Find the selector string for the serial device */
var dis = await DeviceInformation.FindAllAsync(aqs); /* Find the serial device with our selector string */
SerialDevice SerialPort = await SerialDevice.FromIdAsync(dis[0].Id); /* Create an serial device with our selected device */
/* Configure serial settings */
SerialPort.WriteTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.ReadTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.BaudRate = 9600; /* mini UART: only standard baudrates */
SerialPort.Parity = SerialParity.None; /* mini UART: no parities */
SerialPort.StopBits = SerialStopBitCount.One; /* mini UART: 1 stop bit */
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);
Debug.WriteLine(rxBuffer);
Debug.WriteLine("\n");
});
}
});
}
catch (Exception ex)
{
Debug.WriteLine(ex);
}
}
现在可以在https://docs.microsoft.com/en-us/windows/iot-core/learn-about-hardware/pinmappings/pinmappingsrpi
上找到此代码它吐出的数据：
Exception thrown: 'System.NullReferenceException' in Tripmaster.exe
,ANTSTATUS=OPEN*2B
$GPRMC,165556.000,A,5048.7305,N,00305.1325,E,0.00,109.81,270618,,,D*6F
$GPVTG,109.81,T,,M,0.00,N,0.00,K,D*39
$GPGGA,165556.000,5048.7305,N,00305.1325,E,2,7,1.41,8.2,M,47.2,M,,*58
$GPGSA,A,3,20,27,10,32,22,14,08,,,,,,2.41,1.41,1.96*05
$GPGSV,4,1,13,08,73,179,27,18,68,282,,11,54,285,,01,42,274,*7F
$GPGSV,4,2,13,10,37,055,34,27,37,145,28,22,32,214,33,32,32,101,31*70
$GPGSV,4,3,13,28,27,312,,36,25,145,35,14,21,127,31,20,10,052,29*78
$GPGSV,4,4,13,03,09,217,15*41
$GPGLL,5048.7305,N,00305.1325,E,165556.000,A,D*53
$GPTXT,01,01,02,ANTSTATUS=OPEN*2B
$GPRMC,165557.000,A,5048.7305,N,00305.1325,E,0.00,109.81,270618,,,D*6E
$GPVTG,109.81,T,,M,0.00,N,0.00,K,D*39
$GPGGA,165557.000,5048.7305,N,00305.1325,E,2,7,1.41,8.2,M,47.2,M,,*59
$GPGSA,A,3,20,27,10,32,22,14,08,,,,,,2.41,1.41,1.96*05
$GPGSV,4,1,13,08,73,179,26,18,68,282,,11,54,285,,01,42,274,*7E
$GPGSV,4,2,13,10,37,055,33,27,37,145,27,22,32,214,32,32,32,101,30*78
$GPGSV,4,3,13,28,27,312,,36,25,145,34,14,21,127,30,20,10,052,29*78
$GPGSV,
Exception thrown: 'System.NullReferenceException' in System.Private.CoreLib.ni.dll
我需要运行此多线程，因为我需要更新GUI并存储数据和处理数据，并从本地存储中获取数据并显示它。但这超出了这个问题的范围。这里的问题是，我每秒都会收到新的GPS数据，但是它崩溃了，我不知道为什么...
答案 0 :(得分：2)
'System.NullReferenceException'发生在此行：var dis = await DeviceInformation.FindAllAsync(aqs);，因为您反复调用SerialDevice.GetDeviceSelector("UART0");，但是只有第一次获得UART0设备时，您才会得到null的结果{{ 1}}。
正确的格式是将设备初始化一次，并在while循环中读取日期。例如这样的
aqs例如，您可以在按钮单击事件中调用上述函数以启动读取操作：
private async void read_gps_data(string port = "UART0", int baud = 9600)
{
string aqs = SerialDevice.GetDeviceSelector("UART0"); /* Find the selector string for the serial device */
var dis = await DeviceInformation.FindAllAsync(aqs); /* Find the serial device with our selector string */
SerialDevice SerialPort = await SerialDevice.FromIdAsync(dis[0].Id); /* Create an serial device with our selected device */
/* Configure serial settings */
SerialPort.WriteTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.ReadTimeout = TimeSpan.FromMilliseconds(1000);
SerialPort.BaudRate = 9600; /* mini UART: only standard baudrates */
SerialPort.Parity = SerialParity.None; /* mini UART: no parities */
SerialPort.StopBits = SerialStopBitCount.One; /* mini UART: 1 stop bit */
SerialPort.DataBits = 8;
/* Read data in from the serial port */
const uint maxReadLength = 1024;
DataReader dataReader = new DataReader(SerialPort.InputStream);
string rxBuffer = "";
while (true)
{
await Task.Run(async () =>
{
try
{
uint bytesToRead = await dataReader.LoadAsync(maxReadLength);
rxBuffer = dataReader.ReadString(bytesToRead);
Debug.WriteLine(rxBuffer);
Debug.WriteLine("\n");
}
catch (Exception ex)
{
Debug.WriteLine(ex);
}
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
{
// Update UI here
receivedData.text = rxBuffer;
});
});
}
}