C# Serial communication with arduino

Question

I'm trying to communicate with my arduino from my pc. I'm sending 1,0,0,0 in a loop and the arduino sends the received data back. However, instead of getting 1,0,0,0 back, this is what I get:

1000
1000
1000
1000
1000
1000
1000
0011
0000
0010
0100
1001
0000
0011
0000

As you can see, it works at the beginning, but starts to get weird after a few messages. Instead of sending 3 0's it sent 5. Why is that?

Here is my code:

C# Application:

class Program
{
    SerialPort p;

    static void Main(string[] args)
    {
        Program p = new Program();
        p.initialize();
    }
    private void initialize()
    {
        p = new SerialPort("COM3", 115200);
        p.Open();

        byte[] data = { 1, 0, 0, 0 };

        Thread t = new Thread(reading);
        t.Start();

        while(true)
        { 
            p.Write(data, 0, data.Count());
        }
        Console.ReadLine();
    }
    private void reading()
    {
        while (true)
        {
            Console.WriteLine(p.ReadLine());
        }
    }
}

Arduino:

void setup()
{
    Serial.begin(115200);
    delay(5000);
    Serial.println("Program started....");
}

void loop()
{
    for (int i = 0;i<4;i++)
    {
        Serial.print(Serial.read());
    } 
    Serial.println(); 
    delay(500);
}

Answer 1

I think the problem is caused by your 500 ms delay in the Arduino loop.

The PC is sending characters as fast as it can.

However the the Arduino receives 4 characters and then delays 1/2 a second (during the delay the PC could send 62,000 characters).

For a while the Arduino serial receive routine puts the characters into a buffer. But after it receives a few correctly the buffer is full and starts overwriting old characters with the new characters received.

To verify this is the problem, remove the line delay(500); from your Arduino code and add a delay to the PC after the line: p.Write(data, 0, data.Count());

Also, how does Console.ReadLine(); ever get executed since if is after your while(true) infinite loop?