What is wrong with sending data to arduino from serial port?

Using Arduino Motors, Mechanics, Power and CNC
1

I am trying to control stepper motor via serial-port with c# winform app.

In my code i am generating real-time data with timer whose time interval is 30 ms. Generated data is 8 bits pixel number.

Baudrate is 250000. StepsPerRevolution is 240.

The code i use is for sending data to arduino is as given below. I am also using label to see pixel numbers and their difference.

private void SendDataToArduino()
    {
        int stepsperrpm = 360/240;
        if (serialPort1.IsOpen)
        {
            if (currentPix <= previousPix)
            {
                serialPort1.Write("C," + Convert.ToString(stepsperrpm * (previousPix - currentPix)) + "," + Convert.ToString(25) + "\r\n");
            }
            else if (currentPix > previousPix)
            {
                serialPort1.Write("W," + Convert.ToString(stepsperrpm * (currentPix - previousPix)) + "," + Convert.ToString(25) + "\r\n");
            }
        }
    }

The arduino code i am using is:

#include <Stepper.h>
int stepsPerRevolution = 12800; //12800;
Stepper stepper1 = Stepper(stepsPerRevolution, 2,3,4,5);//,3,7,8);

String data[3];  
int index = 0;  
float steps = 0.0;


void setup() {
  stepper1.setSpeed(10);
  Serial.begin(250000);
}


void loop() {
  if (Serial.available()) {
    data[index] = Serial.readStringUntil(',');
    Serial.print("data read: "); Serial.println(data[index]);
    index++;
    if (index == 3) {
      index = 0;
      steps = stepsPerRevolution / 360.0 * data[1].toInt();
      stepper1.setSpeed(data[2].toInt());
      if (data[0] == "C") stepper1.step(steps);
      else if (data[0] == "W") stepper1.step(-steps);
    }
  }
}

What is wrong with sending data to arduino from serial port? Stepper does not move at all or sometimes only rotates in one direction then stops.

In addition C# winform app is also freezing in time.I am sure that i am getting pixel numbers correctly as i show in picture.

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I tried using serialPort.Write(), serialPort.WriteLine() and adding \r\n and of thecode to be sure that arduino receive the data correctly. But i am not able to be successed.

2

When you print the received data does it look correct ?

Note that the data sent includes a CR and LF. Have you taken that into account in the Arduino code ?

3

Transferring data as a string is a very bad idea if you need a fast communication. You lost a time first when convert data to string, then when transfer string data (the length of converted string will be in general a three times more than the lentgh of the binary data) and finally you need an additional time to convert string to data again.

Why do not transfer the data as bytes instead of strings?

4

As shown in labels ont right side, data printed correctly.

I will check your second suggestion.

5

By the way - the expression below will be ALWAYS exactly 1.

is it what you intended?

6

Can you show me any example for that? I am newbie. Sorry.

7

int stepsPerRevolution = 12800; //12800;
Which stepper motor has 12800 steps per revolution.
Leo..

8

I recommend looking at the serial input basics tutorial. It has robust and non-blocking serial input methods. Example 6 has code for receiving byte data.

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9

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