private async Task <byte> OneWireBitAsync(byte b)
{
var bit = b > 0 ? 0xFF : 0x00;
DataWriteObject.WriteByte((byte)bit);
await DataWriteObject.StoreAsync();
await DataReaderObject.LoadAsync(1);
var data = DataReaderObject.ReadByte();
return((byte)(data & 0xFF));
}
/// <summary>
/// ReadAsync
/// Task to read PMTK sentences.
/// Performs sentence assembly, calls parsing routine
/// </summary>
/// <param name="cancellationToken"></param>
/// <returns>async Task</returns>
private async Task ReadAsync(CancellationToken cancellationToken)
{
Task <UInt32> loadAsyncTask;
uint ReadBufferLength = 128;
UInt32 bytesRead = 0;
// Set InputStreamOptions to complete the asynchronous read operation when one or more bytes is available
DataReaderObject.InputStreamOptions = InputStreamOptions.Partial;
int retries = 5;
string rawSentence = "";
string leftovers = "";
while ((!cancellationToken.IsCancellationRequested) && (retries > 0))
{
try
{
while (true)
{
// If task cancellation was requested, comply
cancellationToken.ThrowIfCancellationRequested();
// Create a task object to wait for data on the serialPort.InputStream
loadAsyncTask = DataReaderObject.LoadAsync(ReadBufferLength).AsTask(cancellationToken);
// Launch the task and wait
bytesRead = await loadAsyncTask;
if (bytesRead > 0)
{
rawSentence = DataReaderObject.ReadString(bytesRead);
rawSentence = string.Concat(leftovers, rawSentence);
string[] splitSentences = rawSentence.Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
leftovers = "";
foreach (string str in splitSentences)
{
if ((str.Length >= 3) && (str.LastIndexOf('*') == str.Length - 3))
{
System.Diagnostics.Debug.WriteLine(str);
DispatchSentence(str);
}
else
{
leftovers = str;
}
}
}
retries = 5;
}
}
catch (OperationCanceledException ex)
{
System.Diagnostics.Debug.WriteLine(string.Format("Exiting GPS read task"));
}
catch (ArgumentOutOfRangeException ex)
{
//do nothing. this tends to sort itself out eventually
//System.Diagnostics.Debug.WriteLine(string.Format("ArgumentOutOfRangeException: {0}", ex.Message));
for (int b = 0; b < bytesRead; b++)
{
DataReaderObject.ReadByte();
// bytesRead--;
}
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(string.Format("Error reading from GPS: {0}", ex.Message));
leftovers = "";
retries--;
}
}
SerialPort.Dispose();
SerialPort = null;
}