internal ArduinoResponse Send(ArduinoRequest request)
{
var sendRetries = 0;
while (sendRetries++ < MaxSendRetries - 1)
{
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 - 1)
{
logger.Debug("Unable to get sync ... trying again ({0}/{1}).", syncRetries, MaxSyncRetries);
}
if (!hasSync)
{
var errorMessage = string.Format("Unable to get sync after {0} tries!", MaxSyncRetries);
logger.Fatal(errorMessage);
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.Bytes.ToArray();
var requestBytesLength = requestBytes.Length;
if (!ExecuteCommandHandShake(request.Command, (byte)requestBytesLength))
{
var errorMessage = string.Format("Unable to configure command handshake for command {0}.", request);
logger.Fatal(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.Command;
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;
Write(packetBytes, 0, requestBytesLength + 4);
// Write out all bytes written marker (FA)
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
numberOfBytesToRead = 2;
WaitForBytes(numberOfBytesToRead);
var responseBytes = ReadCurrentReceiveBuffer(numberOfBytesToRead);
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);
logger.Fatal(errorMessage);
throw new IOException(errorMessage);
}
// Read x responsebytes
numberOfBytesToRead = responseLength;
if (BytesToRead < numberOfBytesToRead)
{
WaitForBytes(numberOfBytesToRead);
}
responseBytes = ReadCurrentReceiveBuffer(numberOfBytesToRead);
return(ArduinoResponse.Create(responseBytes));
}
catch (TimeoutException ex)
{
logger.Debug(ex, "TimeoutException in Send occurred, retrying ({0}/{1})!", sendRetries, MaxSendRetries);
}
catch (Exception ex)
{
logger.Debug(ex, "General exception in Send occurred, retrying ({0}/{1})!", sendRetries, MaxSendRetries);
}
}
return(null);
}
internal ArduinoResponse Send(ArduinoRequest request, int maximumSendRetries = maxSendRetries)
{
var sendRetries = 0;
while (sendRetries++ < maximumSendRetries)
{
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)
{
string errorMessage = $"Unable to get sync after {maxSyncRetries} tries!";
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.
byte[] requestBytes = request.Bytes.ToArray();
int requestBytesLength = requestBytes.Length;
if (!ExecuteCommandHandShake(request.Command, (byte)requestBytesLength))
{
string errorMessage = $"Unable to configure command handshake for command {request}.";
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.Command;
packetBytes[1] = (byte)requestBytesLength;
Buffer.BlockCopy(requestBytes, 0, packetBytes, 2, requestBytesLength);
ushort 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;
serialPort.Write(packetBytes, 0, requestBytesLength + 4);
// Write out all bytes written marker (FA)
serialPort.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
byte[] responseBytes = ReadCurrentReceiveBuffer(2);
byte startOfResponseMarker = responseBytes[0];
byte responseLength = responseBytes[1];
if (startOfResponseMarker != CommandConstants.StartOfResponseMarker)
{
string errorMessage = $"Did not receive start of response marker but {startOfResponseMarker}!";
throw new IOException(errorMessage);
}
// Read x responsebytes
responseBytes = ReadCurrentReceiveBuffer(responseLength);
return(ArduinoResponse.Create(responseBytes));
}
catch (Exception) {
// ignored
}
}
return(null);
}