My unity won't read a string data from Arduino to Unity

Code (CSharp):

1.  
2. using System.Collections;
3. using System.Collections.Generics;
4. using UnityEngine;
5. using System.IO.Ports;
6. using System.Threadings;
7.  
8. public class sample: MonoBehavior
9. {
10. SerialPort sp = new SerialPort("COM3", 9600)
11. public GameObject Image;
12.  
13. void Start()
14. {
15. sp.close();
16. sp.Open();
17. sp.ReadTimeout = 1;
18. }
19.  
20. void Update()
21. {
22. if(sp.IsOpen)
23. {
24. try
25. {
26. ArduinoString(sp.ReadLine());
27. print(ArduinoString);
28. }
29. catch(System.Exception)
30. {
31. }
32. }
33.  
34. void ArduinoString(string txt)
35. {
36. if(txt == "r")
37. {
38. Image.setActive(true);
39. }

Arduino Code

Code (Arduino):

1.  
2. void setup()
3. {
4. Serial.begin(9600);
5. Serial.write("r");
6. Serial.flush();
7. }
8. void loop()
9. {
10.  
11. }
12.  

 

You are calling sp.ReadLine(), which, according to the docs, reads until it reaches a newline character. Since your Arduino doesn't send a newline, sp.ReadLine() will throw a TimeoutException after your assigned read timeout of 1ms (which might not be enough time to read something substantial anyways)

 

Yeah it does work on my Serial Monitor.

 

And About the video you suggested when I try on Serial Monitor the "r" appeared but when it's comes to unity it doesn't appear on my console. print(ArduinoString);

 

What should I do?
Should I use Serial.println();?

 

Or, in your Arduino code, try

Code (csharp):

1. Serial.write("r\n")

You may also want to increase your sp.ReadTimeout. 10 is still quite fast.

Also, don't discount the suggestion that your Arduino is sending the message before Unity is listening. You could try moving the Serial.write into the loop.