Yet another SerialPort thread...

Hi folks,

I searched through many threads here after trying my own solution with regular SerialPort class of .NET/mono. In case anyone is looking for a similar simple solution here it is.

TLDR Summary: I read from the serial port byte by byte into a buffer, where I consume it 5 bytes at a time.

So I define a serialPort object like this:

Code (CSharp):

1. private System.IO.Ports.SerialPort serialPort;
2. private List<byte> inputBuffer;
3. private int messageLength;
4.  
5. void Start ()
6. {
7.     messageLength = 5;
8.     inputBuffer = new List<byte>(1000);
9.     serialPort = new System.IO.Ports.SerialPort();
10.     serialPort.BaudRate = 115200;
11.     serialPort.PortName = "COM7";
12.     serialPort.ReadTimeout = 1;
13.     try {
14.         serialPort.Open();
15.         if (!serialPort.IsOpen)
16.             Debug.LogError("Could not open Serial Port");
17.         else
18.             Debug.Log("Serial port is open!");
19.     }
20.     catch(Exception exc)
21.     {
22.         Debug.LogException(exc);
23.     }
24. }

So my Update becomes:

Code (CSharp):

1.  
2. void Update()
3. {
4. // clear input buffer if already filled
5. ReadFromInputBuffer();
6.  
7. int byteRead = 0;
8. try
9. {
10. while (true)
11. {
12. byteRead = serialPort.ReadByte();
13. if (byteRead == -1)
14. break;
15. inputBuffer.Add((byte)byteRead);
16. }
17. }
18. catch
19. {
20. // timeout exceptions are supressed
21. }
22. }
23.  
24.  

I read from the input buffer like this:

Code (CSharp):

1. private void ReadFromInputBuffer()
2. {
3.     while (inputBuffer.Count >= messageLength)
4.     {
5.         byte[] buffer = new byte[messageLength];
6.         inputBuffer.CopyTo(0, buffer, 0, messageLength);
7.         inputBuffer.RemoveRange(0, messageLength);
8.      
9.         // handle data in buffer ...
10.     }
11. }

Cheers

Edit: Some background:
For some reason you cannot use DataReceived event or read BytesToRead property of SerialPort class in Unity.

 

It's a hold post but seems the only real, rapid solution!! Thanks a lot!!
So how it's work, why read from a buffer doesn't slow down the frame read?