public SbepMessage ReceiveSbep()
{
var i = 0;
SbepMessage message = null;
var sw = Stopwatch.StartNew();
while (sw.ElapsedMilliseconds < 1000 && i < _receiveBuffer.Length)
{
var avail = _port.BytesToRead;
if (avail == 0)
{
Thread.Sleep(20);
continue; //Don't restart stopwatch.
}
_port.Read(_receiveBuffer, i, avail);
i += avail;
message = new SbepMessage(_receiveBuffer, i);
if (!message.Incomplete)
{
break;
}
sw.Restart(); //Give some more time for bytes
}
if (message == null || message.Incomplete || message.Invalid)
{
UpdateStatus("Timeout or Checksum Error");
}
else
{
UpdateStatus("Received: " + String.Join(" ", Array.ConvertAll(message.Bytes.ToArray(), x => x.ToString("X2"))));
}
return(message);
}
public void SendSbep(SbepMessage message)
{
int attempts = 0;
while (true)
{
_port.DiscardInBuffer();
_port.DiscardOutBuffer();
var packetSize = message.Bytes.Length;
UpdateStatus("Sending " + String.Join(" ", Array.ConvertAll(message.Bytes, x => x.ToString("X2"))));
_port.Write(message.Bytes, 0, packetSize);
//Every byte sent is echoed back since TX/RX lines are connected.
//They have to be read back from the serial port before getting to a response packet.
var sw = Stopwatch.StartNew();
byte[] echo = new byte[packetSize];
while (sw.ElapsedMilliseconds < 1000)
{
if (_port.BytesToRead < packetSize)
{
Thread.Sleep(10);
continue;
}
_port.Read(echo, 0, packetSize);
break;
}
//A check could be made to see if bytes matched what was sent. But it's kind of pointless
//as it is not the radio echoing the bytes, it's just the computer hearing itself.
if (echo.Max() == 0x00)
{
if (attempts == 4)
{
throw new Exception("RIB or interface cable does not appear to be connected to the computer. Did the cable to the computer come loose?");
}
Thread.Sleep(500);
attempts++;
continue;
}
if (!message.ExpectAck)
{
return;
}
//Now look for actual response from the radio.
sw = Stopwatch.StartNew();
int ack = 0;
while (sw.ElapsedMilliseconds < 1000)
{
if (_port.BytesToRead < 1)
{
Thread.Sleep(10);
continue;
}
ack = _port.ReadByte(); break;
}
if (ack == 0x50)
{
return;
}
if (attempts == 4)
{
throw new Exception("The radio failed to ackowledge command. Try power cycling the radio and running the operation again.");
}
Thread.Sleep(500);
attempts++;
}
}
