communication from arduino to C# forms app

Question

I'm following this tutorial. The goal is to receive periodic data from the arduino via serial port. I've been struggling with this for a while now. The com port connection is fine as i'm unable to connect with another terminal program to the arduino when my c# app is running ( port is already connected). At this point the SerialListen thread should start but this doesn't happen.

namespace TestReceiveArduino
{
public partial class Form1 : Form
{
    //object serialport to listen usb
    System.IO.Ports.SerialPort Port;

    //variable to check if arduino is connect
    bool IsClosed = false;

    public Form1()
    {
        InitializeComponent();


        //configuration of arduino, you check if com3 is the port correct, 
        //in arduino ide you can make it
        Port = new System.IO.Ports.SerialPort();
        Port.PortName = "COM11";
        Port.BaudRate = 9600;
        Port.ReadTimeout = 500;

        try
        {
            Port.Open();
            Console.WriteLine("open port ");


        }
        catch { }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        //A Thread to listen forever the serial port
        Console.WriteLine("start thread ");
        Thread Hilo = new Thread(ListenSerial);
        Hilo.Start();
    }


    private void ListenSerial()
    {
        Console.WriteLine("start listener");
        while (!IsClosed)
        {
            Console.WriteLine("in while");

            try
            {
                //read to data from arduino
                string AString = Port.ReadLine();

                //write the data in something textbox
                txtSomething.Invoke(new MethodInvoker(
                    delegate
                    {
                        txtSomething.Text = AString;
                    }
                    ));

            }
            catch { }
        }
    }

    private void Form1_FormClosed(object sender, FormClosedEventArgs e)
    {
        //when the form will be closed this line close the serial port
        IsClosed = true;
        if (Port.IsOpen)
            Port.Close();
    }
}
}

My arduino is sending data, i've checked this with terminal software. I'm also using the correct COM port I have some experience with c# but i'm new to threads. What could be the reason for this?

Answer 1

OK:

1. See if these changes help:

   namespace TestReceiveArduino
   {
       public partial class Form1 : Form
       {
           //object serialport to listen usb
           System.IO.Ports.SerialPort Port;
   
           //variable to check if arduino is connect
           bool IsClosed = false;
   
           public Form1()
           {
               InitializeComponent();  
           }
   
           private void Form1_Load(object sender, EventArgs e)
           {
               try
               {
                   // Connect to Arduino
                   Port = new System.IO.Ports.SerialPort();
                   Port.PortName = "COM11";
                   Port.BaudRate = 9600;
                   Port.ReadTimeout = 500;
                   Port.Open();
                   Console.WriteLine("Port successfully opened: Name: {0}, Baud: {1}, ReadTimeout: {2}", Port.PortName, Port.BaudRate, Port.ReadTimeout);
   
                  //A Thread to listen forever the serial port
                  Console.WriteLine("start thread ");
                  Thread Hilo = new Thread(ListenSerial);
                  Hilo.Start();
               }
               catch (Exception ex)
               { 
                   Console.WriteLine(ex.Message);
               }
           }
           ...
   

2. I moved "Open Serial Connection" and "Start Listener Thread" to the same place (Form1_Load), and wrapped both in the same try/catch block. You might even want to move the "try/catch" to a higher level (e.g. so you can display any exceptions in your Windows GUI).

3. I assume you're using Microsoft VisualStudio (e.g. MSVS Express 2019) as your GUI, correct? Definitely familiarize yourself with your IDE's debugger; definitely get in the habit of stepping through the code as you're developing it.

4. Your next steps:

   • Verify the code gets to "Open Serial Connection", and verify that it opens correctly (e.g.prints "Port successfully opened...").
   • Verify the code then gets to "ListenSerial()", and prints "start listener" and "in while" at least once.

'Hope that helps...