Matlab and arduino: serial port connection

[lcr2139]

Hello, I am trying to hook up MATLAB to my arduino. I am trying to write a number to the serial port in the arduino IDE and retrieving the same number in the MATLAB IDE. My arduino code is:

void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}

void loop() {

if (Serial.available()){
Serial.println(3);

delay(100); // delay in between reads for stability
}
}


And my MATLAB code looks like:

%s = serial('COM9');
s = serial ( 'COM9' , 'BaudRate' , 9600, 'terminator' , 'CR' );
%set(s,'BaudRate',4800);
fopen(s);

fprintf(s,'*IDN?')
fread(s)
disp(s)
out = fscanf(s);
fclose(s)
delete(s)
clear s

and the MATLAB output looks like:

10
51
13
10
51
13
10
51
13

How can I change this so only "3" comes out?
Thanks!

 

[jfgobin]

Double check that you have the right parity and numbers of stop bits.

 

[lcr2139]

Sorry, I'm pretty new at this. What are parity and numbers of stop bits?

 

[jfgobin]

In http://home.iitb.ac.in/~rahul./ITSP/serial_comm_matlab.pdf the guy uses LF for the terminator. Try it.

J.

 

[lcr2139]

LF gives a Terminator error so I have to use CR.

 

[jfgobin]

Okay, then try the following

Arduino

void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600,SERIAL_8N1);
}

void loop() {
  if (Serial.available()){
    Serial.println(3);
    delay(100); // delay in between reads for stability
    }
}

On the Matlab side:

s = serial ( 'COM9' , 'BaudRate' , 9600, 'DataBits', 8, 'Parity', 'none', 'StopBits', 1, 'terminator' , 'CR' );
fopen(s);
fprintf(s,'*IDN?')
fread(s)
disp(s)
out = fscanf(s);
fclose(s)
delete(s)
clear s

This will make sure that everything serial is set the same on both ends of the cable.

Also, something I have some difficulties understanding: you are using fread() and fscanf() in the same run. Why? What's the content of the variable out?