Unity is giving error 'InvalidOperationException: Specified port is not open.'

Unity Engine
,
1

Hey everyone,
I am trying to connect an Arduino Uno to Unity, and had been successful the first time when there was only a button being controlled. However, after implementing a joystick, unity gives my the error
InvalidOperationException: Specified port is not open
So I use the code

foreach (string str in SerialPort.GetPortNames())
        {
            Debug.Log(string.Format("Existing COM port: {0}", str));
        }

To check if my port exists, and, sure enough unity does return COM8, however after that it again instantly gives the error back.

This is my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.IO.Ports;

public class ARDUINO : MonoBehaviour
{
    SerialPort Serial = new SerialPort("COM8", 9600);
    public string reStr;
    public Rigidbody2D rb;
    public float speedyBoi = 10;
    public string[] data;

    // Start is called before the first frame update
    void Start()
    {
        Serial.Open();
    }

    // Update is called once per frame
    void Update()
    {
        foreach (string str in SerialPort.GetPortNames())
        {
            Debug.Log(string.Format("Existing COM port: {0}", str));
        }
        reStr = Serial.ReadLine();

        string[] data = reStr.Split(",");


        rb.transform.position = new Vector3(rb.transform.position.x + float.Parse(data[0]) * Time.deltaTime, rb.transform.position.x + float.Parse(data[1]) * Time.deltaTime, 0);

    }
}

Please advice me on what I can do, thank you in advanced.

2

Buttons and Joysticks should have absolutely nothing to do with ports.

Most likely you introduced a bug in your code when you changed to joystick.

The other possibility is that the port software drivers have an issue, which isn’t uncommon under Windows. This is usually dealt with by rebooting the system.

Otherwise, time to start debugging your code and setup!

Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is
  • you’re getting an error or warning and you haven’t noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the names of the GameObjects or Components involved?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: How To - Capturing Device Logs on iOS or this answer for Android: How To - Capturing Device Logs on Android

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

When in doubt, print it out!™

Note: the print() function is an alias for Debug.Log() provided by the MonoBehaviour class.