I am facing a problem in serial communication of matlab and arduino.

I am trying to do serial communication of matlab and arduino. Serial communication is not so much difficult between arduino and matlab but my problem is different.

I want to make 3 edit boxes in GUI and want to send the numeric values entered in boxes to arduino. But now i am trying to send only one value from one edit box to arduino. Arduino is not performing the job.

Here is my matlab code.

function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'Value') returns position of slider
%        get(hObject,'Min') and get(hObject,'Max') to determine range of slider
x =str2num(get(handles.edit1,'String'));
disp('Value entered: ')
disp(x)
delete(instrfind({'Port'},{'COM6'}));
s=serial('COM6');
s.BaudRate=9600;
fopen(s);
disp('After OPEN')
disp(s)
fprintf(s,x);
fclose(s);
disp('After CLOSE')
disp(s)

After entering number in edit box i get this in command windows.

Value entered: 
       10000

After OPEN

   Serial Port Object : Serial-COM6

   Communication Settings 
      Port:               COM6
      BaudRate:           9600
      Terminator:         'LF'

   Communication State 
      Status:             open
      RecordStatus:       off

   Read/Write State  
      TransferStatus:     idle
      BytesAvailable:     0
      ValuesReceived:     0
      ValuesSent:         0

After CLOSE

   Serial Port Object : Serial-COM6

   Communication Settings 
      Port:               COM6
      BaudRate:           9600
      Terminator:         'LF'

   Communication State 
      Status:             closed
      RecordStatus:       off

   Read/Write State  
      TransferStatus:     idle
      BytesAvailable:     0
      ValuesReceived:     0
      ValuesSent:         2

And here is my arduino code.

    void setup() {
    // put your setup code here, to run once:
    pinMode(13, OUTPUT);
    Serial.begin(9600);
  }

void loop() {
  // put your main code here, to run repeatedly:
  if(Serial.available()>0) // check if Serial data is available to read
  {
    int x=Serial.read();
    //int x = Serial.parseInt();
    //int y = Serial.parseInt();
    //int z = Serial.parseInt();

      digitalWrite(13, HIGH);
      delay(x);
      digitalWrite(13, LOW);
      delay(x);
      /*digitalWrite(13, HIGH);
      delay(y);
      digitalWrite(13, LOW);
      delay(y);
      digitalWrite(13, HIGH);
      delay(z);
      digitalWrite(13, LOW);
      delay(z);*/

    }
  }

Answer 1

[Walter Roberson]

You have

fprintf(s,x)

The default format for fprintf to serial port is '%s\n', so you have done the equivalent of

fprintf(s, '%s\n', x)

Conversion of numeric arguments for %s works like uint8(x) (I think; I am not completely sure). Your 10000 would (I think) be converted to 255 and the single byte with value 255 sent. Followed by the terminator.

Your arduino code uses Serial.read() which expects only a single byte.

I suggest you read https://www.arduino.cc/en/Tutorial/ReadASCIIString

Answer 2

[Haroon Aziz]

now i am using this arduino code but not getting any results.

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

void loop()
{
  while (Serial.available()) // check if Serial data is available to read
  {

      int x = Serial.parseInt();
      int y = Serial.parseInt();
      int z = Serial.parseInt();

    digitalWrite(13,HIGH);
    delay(x);
    digitalWrite(13,LOW);
    delay(x);
    digitalWrite(13,HIGH);
    delay(y);
    digitalWrite(13,LOW);
    delay(y);
    digitalWrite(13,HIGH);
    delay(z);
    digitalWrite(13,LOW);
    delay(z);  
    }
  }

also i have tried changing in matlab command.

[Walter Roberson]

Your MATLAB code is sending one value but your arduino code expects three.

Test the MATLAB side with some constant data such as

fprintf(s, '%d %d %d\n', [42, 153, 287]);

Answer 3

[husam alrajab]

I am facing the same problem plz let me know if you solved it ??