Arduino + unity

Projects General Guidance
1

Hello everyone, I want to start using Unity (game engine) with Arduino. In unity I have 2 buttons, each one sends a different message to the arduino, the messages are "1" and "2". Arduino receives the message and decides to turn on or off the LED on the 13th pin. First, look at the codes.

Here is the Unity C# code:

using UnityEngine;
using System.Collections;
using System.IO.Ports;
public class SerialPortTest : MonoBehaviour 
{
	public static SerialPort sp = new SerialPort("COM3", 9600, Parity.None, 8, StopBits.One);
	public int count = 0;
	public string message, message1;
	public int message2;

	void Start () 
	{
	OpenConnection();
	}

	void OnGUI() 
	{
		GUI.Label(new Rect(230, 60, 500, 20), "" + message1 + " Received " + message2);
		GUI.Label(new Rect(120, 10, 500, 30), "Status: "+message);
		if (GUI.Button(new Rect(10, 60, 200, 30), "Light on"))
		{
			if (sp.IsOpen) 
			{
			message1 = "Sent 1";
			sp.Write("1");	
			message2 = sp.ReadByte();
			}
		}
		if (GUI.Button(new Rect(10, 150, 200, 30), "Light off"))
		{
			if (sp.IsOpen) 
			{
			message1 = "Sent 2";
			sp.Write("2");	
			message2 = sp.ReadByte();
			}
		}
    }
	void Update () 
	{
	}

	public void OpenConnection() 
	{
		if (sp != null) 
		{
			if (sp.IsOpen) 
			{
				sp.Close();
				message = "Closing port, because it was already open!";
			}
			else 
			{
				sp.Open();  // opens the connection
				sp.ReadTimeout = 100;  // sets the timeout value before reporting error
				message = "Port Opened!";
			}
		}
		else 
		{
			if (sp.IsOpen)
			{
				print("Port is already open");
			}
			else 
			{
				print("Port == null");
			}
		}
	}
	void OnApplicationQuit() 
	{
		sp.Close();
	}

}

And here is the Arduino code:

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT); 
}

void loop() 
{
  if (Serial.available())
  {
     if(Serial.read() == 50){
     Serial.write(30);
     digitalWrite(13, LOW);
  }
  else if(Serial.read() == 49){
     Serial.write(20);
     digitalWrite(13, HIGH);
  }

  }
}

The problem is that I receive the answer in unity only when I send the message "2" to Arduino. It's really strange, if I switch the "if"s with places in the Arduino Code then it works only when I send the "1" message, it seems Arduino doesn't go through the whole loop but just through the first "if".
Could anyone help me with this?
Thanks :wink:

2

This what you, probably, want:

if (Serial.available())
  {
     if(Serial.read() == 50){
     Serial.write(30);
     digitalWrite(13, LOW);
  }
   if(Serial.read() == 49){
     Serial.write(20);
     digitalWrite(13, HIGH);
  }
}
3

Doesn't work, still the same thing, the only way it works right now is like this:

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT); 
}

void loop() 
{
  if (Serial.available())
  {
     if(Serial.read() == 50)
     {
     Serial.write(30);
     digitalWrite(13, LOW);
     }
  }
    if (Serial.available())
  {
     if(Serial.read() == 49)
     {
     Serial.write(20);
     digitalWrite(13, HIGH);
    }
  }
}

But it still works in a glitchy way, sometimes I get the response in unity, sometimes I do not, and when I don't get a response, Unity gives me this error:

TimeoutException: The operation has timed-out.
System.IO.Ports.WinSerialStream.Read (System.Byte[] buffer, Int32 offset, Int32 count)
System.IO.Ports.SerialPort.read_byte ()
System.IO.Ports.SerialPort.ReadByte ()
(wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:ReadByte ()
SerialPortTest.OnGUI () (at Assets/SerialPortTest.cs:30)

I think it must have something to do with the timeout, but I don't know what :confused:

4

If you only send 1 character over, the first "if (Serial.read)" to occur will get a valid byte - the 2nd if (Serial.read) will read an empty buffer, probably get 255 back as a result and thus not do its Serial.write. So when the first one matches, you good, and if doesn't you are hosed.

Try it this way:

void loop() 
{
  if (Serial.available()){
 incomingBtye = Serial.read() ;  // read the byte
}
switch (incomingByte){
case 0x50:
     Serial.write(30);
     digitalWrite(13, LOW);
     break;
 case 0x49:
     Serial.write(20);
     digitalWrite(13, HIGH);
  break;
// and maybe add something here if get an invalid/unexpected byte:
     Serial.write(incomingByte);

}// end switch

} // end void loop
5

It needed some tweaking but it works! Thanks a lot!
Here is the final code:

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT); 
}

void loop() 
{
  int incomingBtye = 0;
  if (Serial.available())
  {
    incomingBtye = Serial.read() ;  // read the byte
  }
switch (incomingBtye)
{
case 50:
     Serial.write(30);
     digitalWrite(13, LOW);
     break;
 case 49:
     Serial.write(20);
     digitalWrite(13, HIGH);
  break;
}
}
6

Glad to help :slight_smile: