Serial.write(), without delay

Projects Programming
1

Hello, I'm trying to send data back and forth between Unity and my Arduino. The arduino code looks like this:

#include <LiquidCrystal.h>

LiquidCrystal lcd(2, 3, 4, 9, 10, 11, 12);

int incNo = 0;

void setup()
{
    Serial.begin(9600);
    lcd.begin(16, 2);
    lcd.print("Unity Testing");
}

void loop()
{       	
	GetInput();
	SendOutput();
}

This is how I handle the recived input:

void GetInput()
{
	if(Serial.available())
	{
		char ch = Serial.read();
		if(ch >= '0' && ch <= '9')
		{
			incNo = (ch - '0');
			lcd.setCursor(0, 1);
 			lcd.print(incNo);
		}
	}
}

This is how I send the recived input back. The problem with this is that the delay makes the game laggy.
But if I remove the delay Unity doesn't react to the input.
I can see that the Arduino recived my input from Unity on the LCD display when the delay is gone.
But it doesn't seem like it sends it back to Unity.
Is there any way around this?

void SendOutput()
{	
	delay(500);
	Serial.write(incNo);

}

This is how I open the connection in Unity:

public class SerialPortConnector : MonoBehaviour
{
    //the connection is static since there is only allowed this one instance.
    public static SerialPort sp = new SerialPort("COM7", 9600); //POssibility of a form to change properties for connection and close it aswell. GUI.
    
    // Use this for initialization
    void Start()
    {
        OpenConnection();
    }

    public static void OpenConnection()
    {
        if (sp != null)
        {
            if (sp.IsOpen)
            {
                sp.Close();
                Debug.Log("Port closed");
            }
            else
            {
                sp.Open();
                Debug.Log("Port open");
            }
        }
        else
        {
            if (sp.IsOpen)
            {
                Debug.Log("Port is already open");
            }
            else
            {
                Debug.Log("Port == null");
            }
        }
    }

    void OnApplicatioQuit()
    {
        sp.Close();
    }
}

And this is how I send and recive data:

void Update () 
    {
        if (Input.GetKeyDown(KeyCode.A))
        {
          SerialPortConnector.sp.Write("1");
        }
        if (Input.GetKeyDown(KeyCode.D))
        {
            SerialPortConnector.sp.Write("2");
        }
        if (SerialPortConnector.sp.IsOpen)
        {
            myInt = SerialPortConnector.sp.ReadChar();
            print(myInt);
        }

  }
2

How often did you intend the sketch to send incNo over the serial port? I imagine it would make sense to do this once each time you receive a command, but your sketch repeats the current value each time round the loop i.e. much much faster than it is receiving commands.

I suggest you do the Serial.write in the same place that you do the lcd.print, so that it is only done once per command. I think this will improve the performance dramatically.

3

For some reason Unity crashes if I do

void GetInput()
{
	if(Serial.available())
	{
		char ch = Serial.read();
		if(ch >= '0' && ch <= '9')
		{
			incNo = (ch - '0');
			lcd.setCursor(0, 1);
 			lcd.print(incNo);
			Serial.write(incNo);
			
		}
		
	}
}
4

What is a unity?

5

Unity is a game engine

www.unity3d.com

6

Keep in mind that serial transmission is asynchronous. With your loop and delay you are basically turning the Serial.write() into a blocking call. Mucher longer than the transmission takes.

Call Serial.flush() after the write. That will cause the Arduino to at least wait until the byte is sent.

7

Thanks a lot for your suggestion. I'm calling Serial.flush() now but it seems like it doesn't reacht to new input when the delay is gone.

my SendOutput() looks like this now

void SendOutput()
{	
	Serial.write(incNo);
        Serial.flush();
}
8

In the case of 0, your C#? code is expecting a character. You are sending the byte 0x0, which isn't a printable character.

Did you really want to write or did you want to print (send ascii 48, instead of 0) from the Arduino?