Uploading sketch in Arduino - matlab

Question

I am working on making an interface between MATLAB and Arduino. In other words, I want to send some data from MATLAB to Arduino. I have written programs both in MATLAB and the Arduino IDE.
MATLAB program:
c = 1;
if (c ~= 0 )
f = 1;
else
disp('vhxhjf');
end
disp(f)
arduino=serial('COM5','BaudRate',9600); % create serial communication object on port COM4
fopen(arduino); % initiate arduino communication
while f
fprintf(arduino,'%s',char(f)); % send answer variable content to arduino
end
fclose(arduino); % end communication with arduino
Code for Arduino:
int ledPin = 13;
int matlabData ;
void setup() {
pinMode(13,OUTPUT);
Serial.begin(9600);
// turn the LED on when we're done
// digitalWrite(13, HIGH);
}
void loop() {
if(Serial.available() > 0 ) {
matlabData = Serial.read();
if ( matlabData != 0) {
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13,LOW);
delay(1000);
}
else
digitalWrite(13,LOW);
}
}
The problem is whenever I am uploading the sketch , this error is being thrown regularly in arduino ide:
avrdude: ser_open(): can't open device "\\.\COM5": The system cannot find the file specified
It was works on the first try, but after that the above error is thrown continuosly .
Also in matlab, after the first try , the following error is thrown:
enter code here
Error using serial/fopen (line 72)
Open failed: Port: COM5 is not available. No ports are available.
Use INSTRFIND to determine if other instrument objects are connected to requested device.
Error in SP (line 65)
fopen(arduino); % initiate arduino communication
>> instrfind
Instrument Object Array
Index: Type: Status: Name:
1 serial open Serial-COM5
2 serial closed Serial-COM5
and also the command instrfind is showing that the com5 port is closed after the first try.
I have tried the solution given in this link but it is didn't work:
http://forum.arduino.cc/index.php?topic=48421.0

Answer 1

This usually happens when you don't close the port.
In your code, when do you close it? When is f changed so the loop exits?
According to these people, you can try to do
delete(instrfindall)
before trying to open the port or
fopen(arduino);
closeFID = onCleanup(#() fclose(arduino));
...
IMHO the second solution looks better (less destructive)
BTW: put a delay or a sleep (I don't know how this is done in ML) in the fprintf loop, otherwise you will send too many data to the poor Arduino...