Reading data from serial port causes unity to hang

Question

Hi all, I have a script that gets values from a serial port from an Arduino, however when I hit play, unity editor hangs. How do I fix this? Thanks!

(this is my code for unity)

 using UnityEngine;
  using System.Collections;
  using System.IO.Ports;
  using System.IO;
  using System;
  using System.Linq;
  using System.Collections;
  using System.Collections.Generic;
  
  public class musicScrip : MonoBehaviour {
  
      private float amount;
      private int var1;
      private int var2;
      private int var3;
  
  
      SerialPort sp = new SerialPort("COM7", 9600);
  
      void Start ()
      {
          sp.Open();
          sp.ReadTimeout = 100;
  
      }
      
      void Update () 
      {
          if (sp.IsOpen)  //youtube tutorial's method 
          {
              try
              {
                  serialEvent (sp);
              }
              catch (System.Exception)
              {
                  throw;
              }
          }
  
      }
  
      void serialEvent(SerialPort myPort)
      {
          string myString = myPort.ReadLine(); //the ascii value of the "|" character
          if(myString != null)
          {
              myString = myString.Trim(); //remove whitespace around our values
              string[] inputs = myString.Substring(2, myString.Length-4).Split(',');
              //now assign your values in processing
              if(inputs.Length == 3)
              {
                  var1 = Int32.Parse(inputs[0]);
                  var2 = Int32.Parse(inputs[1]);
                  var3 = Int32.Parse(inputs[2]);
                  Debug.Log(var1);
          
              
              }
  
          }
      }
  }

Answer 1

Answer by raziel_anarki · Feb 10, 2016 at 04:27 PM

i'm using a similar code for reading from the arduino.

the main difference is that i've set

 serialPort.ReadTimeout = 1;

this means, that the ReadLine will only wait this long (i think it's in msec units) for data.

with such a short timeout, it's possible that ReadLine will find an empty buffer, and throw a TimeoutException so instead i've wrapped it in a try-catch block like this

 try
 {
     Debug.Log ("Read " + serialPort.ReadLine ());
     // do other stuff with the data
 }
 catch (TimeoutException e)
 {
     // no-op, just to silence the timeouts. 
     // (my arduino sends 12-16 byte packets every 0.1 secs)
 }

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Joobei · Jan 16, 2019 at 02:45 PM 0

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In which namespace can I find TimeoutException ? System.ServiceProcess doesn't seem to exist in Unity3D.

Reading data from serial port causes unity to hang

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