/// <summary>
/// <para>Constructor.</para>
/// </summary>
/// <param name="command">The command</param>
/// <param name="errorMessage">The error code</param>
/// <param name="Message">The exception message</param>
public NxtCommunicationProtocolException(NxtCommand command, NxtErrorMessage errorMessage, string Message)
: base(Message.Trim())
{
this.command = command;
this.errorMessage = errorMessage;
}
/// <summary>
/// <para>Constructor.</para>
/// </summary>
/// <param name="command">The command</param>
/// <param name="errorMessage">The error code</param>
/// <param name="Message">The exception message</param>
public NxtCommunicationProtocolException(NxtCommand command, NxtErrorMessage errorMessage, string Message)
: base(Message.Trim())
{
this.command = command;
this.errorMessage = errorMessage;
}
/// <summary>
/// <para>Sends a request for the NXT brick, and if applicable, receive the reply.</para>
/// </summary>
/// <param name="request">The request</param>
/// <returns>The reply as a byte-array, or null</returns>
protected override byte[] Send(byte[] request)
{
lock (serialPortLock)
{
if (!IsConnected)
{
throw new NxtConnectionException("Can't send message: Not connected.");
}
int length = request.Length;
// Create a Bluetooth request.
byte[] btRequest = new byte[request.Length + 2];
btRequest[0] = (byte)(length & 0xFF);
btRequest[1] = (byte)((length & 0xFF00) >> 8);
request.CopyTo(btRequest, 2);
// Write the request to the NXT brick.
serialPort.Write(btRequest, 0, btRequest.Length);
// 0x80 indicates that we should expect a reply.
if ((request[0] & 0x80) == 0)
{
int lsb = serialPort.ReadByte();
int msb = serialPort.ReadByte();
length = msb * 256 + lsb;
byte[] reply = new byte[length];
serialPort.Read(reply, 0, length);
NxtCommand command = (NxtCommand)request[1];
NxtCommand commandEcho = (NxtCommand)reply[1];
if (reply[0] != 0x02)
{
throw new NxtCommunicationProtocolException(command, NxtErrorMessage.UndefinedError, string.Format("Expected a Reply Command byte (0x02); Got 0x{0:X2} instead.", reply[0]));
}
if (commandEcho != command)
{
throw new NxtCommunicationProtocolException(command, NxtErrorMessage.UndefinedError, string.Format("Expected a matching return Command byte (0x{0:X2}); Got 0x{1:X2} instead.", command, commandEcho));
}
NxtErrorMessage statusByte = (NxtErrorMessage)reply[2];
if (statusByte != NxtErrorMessage.Succes)
{
string errorText = "The Status byte indicates an error: Request:";
foreach (byte requestByte in request)
{
errorText += string.Format(" 0x{0:X2}", requestByte);
}
errorText += "; Reply:";
foreach (byte replyByte in reply)
{
errorText += string.Format(" 0x{0:X2}", replyByte);
}
throw new NxtCommunicationProtocolException(command, statusByte, errorText);
}
return(reply);
}
else
{
return(null);
}
}
}
