public object Execute(ArduinoFunction function)
{
var result = port.Send(function);
object netObject = null;
switch (function.ReturnType)
{
case SupportedType.BOOLEANT:
netObject = result[0] == 0 ? false : true;
break;
case SupportedType.CHART:
netObject = (sbyte)result[0];
break;
case SupportedType.UCHART:
netObject = result[0];
break;
case SupportedType.BYTET:
netObject = result[0];
break;
case SupportedType.INTT:
netObject = BitConverter.ToInt16(result, 0);
break;
case SupportedType.UINTT:
netObject = BitConverter.ToUInt16(result, 0);
break;
case SupportedType.LONG:
netObject = BitConverter.ToInt32(result, 0);
break;
case SupportedType.ULONG:
netObject = BitConverter.ToUInt32(result, 0);
break;
case SupportedType.SHORT:
netObject = BitConverter.ToInt16(result, 0);
break;
}
return(netObject);
}
internal byte[] Send(ArduinoFunction request, int maxSendRetries = MaxSendRetries)
{
var sendRetries = 0;
while (sendRetries++ < maxSendRetries)
{
try
{
// First try to get sync (send FF FE FD FC and require FC FD FE FF as a response).
bool hasSync;
var syncRetries = 0;
while (!(hasSync = GetSync()) && syncRetries++ < MaxSyncRetries)
{
}
if (!hasSync)
{
var errorMessage = string.Format("Unable to get sync after {0} tries!", MaxSyncRetries);
throw new IOException(errorMessage);
}
// Now send the command handshake (send FB as start of message marker + the command byte + length byte).
// Expect the inverse (length byte followed by command byte followed by FB) as a command ACK.
var requestBytes = request.GetDataBytes().ToArray();
var requestBytesLength = requestBytes.Length;
if (!ExecuteCommandHandShake(request.FunctionId, (byte)requestBytesLength))
{
var errorMessage = string.Format("Unable to configure command handshake for command {0}.", request);
//logger.Warn(errorMessage);
throw new IOException(errorMessage);
}
// Write out all packet bytes, followed by a Fletcher 16 checksum!
// Packet bytes consist of:
// 1. Command byte repeated
// 2. Request length repeated
// 3. The actual request bytes
// 4. Two fletcher-16 checksum bytes calculated over (1 + 2 + 3)
var packetBytes = new byte[requestBytesLength + 4];
packetBytes[0] = request.FunctionId;
packetBytes[1] = (byte)requestBytesLength;
Buffer.BlockCopy(requestBytes, 0, packetBytes, 2, requestBytesLength);
var fletcher16CheckSum = CalculateFletcher16Checksum(packetBytes, requestBytesLength + 2);
var f0 = (byte)(fletcher16CheckSum & 0xff);
var f1 = (byte)((fletcher16CheckSum >> 8) & 0xff);
var c0 = (byte)(0xff - (f0 + f1) % 0xff);
var c1 = (byte)(0xff - (f0 + c0) % 0xff);
packetBytes[requestBytesLength + 2] = c0;
packetBytes[requestBytesLength + 3] = c1;
serialStream.Write(packetBytes, 0, requestBytesLength + 4);
// Write out all bytes written marker (FA)
serialStream.Write(new[] { CommandConstants.AllBytesWritten }, 0, 1);
// Expect response message to drop to be received in the following form:
// F9 (start of response marker) followed by response length
var responseBytes = ReadCurrentReceiveBuffer(2);
var startOfResponseMarker = responseBytes[0];
var responseLength = responseBytes[1];
if (startOfResponseMarker != CommandConstants.StartOfResponseMarker)
{
var errorMessage = string.Format("Did not receive start of response marker but {0}!", startOfResponseMarker);
throw new IOException(errorMessage);
}
// Read x responsebytes
if (responseLength == 0xfc)
{
return(null);
}
responseBytes = ReadCurrentReceiveBuffer(responseLength);
return(responseBytes);
}
catch (TimeoutException ex)
{
// logger.Debug(ex, "TimeoutException in Send occurred, retrying ({0}/{1})!", sendRetries, MaxSendRetries);
}
catch (Exception ex)
{
// logger.Debug("Exception: '{0}'", ex.Message);
}
}
return(null);
}