Error opening a text file using fopen

disp('Setting up serial communication...');

% Determine which COM port is for microcontroller and change

a = arduino('COM4','Uno');

% Open serial COM port for communication

fopen(a);

set(a,'Timeout',10);

prev_left = [0 0 0 0];

prev_right = [0 0 0 0];

prev_left_flag=0;

prev_right_flag =0;

prev_flag = 2;

check_left = 0;

check_right = 0;

check_straight_right = 0;

check_straight_left = 0;

check_left_right = 0;

check_right_left = 0;

[Stephen23]

a is not a text file, it is an Arduino object.

[NURUL NABILAH]

thank you sir

Answer 1

[Walter Roberson]

It is not necessary to fopen() an arduino object: the arduino() function does any necessary opening of the device.

[NURUL NABILAH]

so for arduino does not any necessary? am i right?

[NURUL NABILAH]

sorry for disturbing you sir. sir can you help me for correcting my coding because my driver motor is not moving.

[Walter Roberson]

The code you posted does not read anything from the device and does not send anything to the device.

[NURUL NABILAH]

%%Initialization of variables and serial communication

clc;

clear all;

close all;

delete(instrfind);

% Set up the COM port for serial communication

disp('Setting up serial communication...');

% Determine which COM port is for microcontroller and change

s = serial('COM4','Parity','none','FlowControl','none','BaudRate',9600);

% Open serial COM port for communication

fopen(s);

set(s,'Timeout',10);

prev_left = [0 0 0 0];

prev_right = [0 0 0 0];

prev_left_flag=0;

prev_right_flag =0;

prev_flag = 2;

check_left = 0;

check_right = 0;

check_straight_right = 0;

check_straight_left = 0;

check_left_right = 0;

check_right_left = 0;

%%Image Capture and Eye Detection

vid=videoinput('winvideo',1); start(vid)

while(vid.FramesAcquired<=25)

      I = getsnapshot(vid);
      I = rgb2gray(I);
      I = imadjust(I);
      I = adapthisteq(I);
      I = imrotate(I,180);
      faceDetector = vision.CascadeObjectDetector('LeftEyeCART');
      j=0;
      left_flag=0;
      right_flag=0;
      bboxes = step(faceDetector, I);
      [m,n] = size(bboxes);
      IFaces = insertObjectAnnotation(I, 'rectangle', bboxes, 'Eye');
      imshow(IFaces), title('Detected eye');
     %%Image Processing     
      TF = isempty(bboxes);
      if (TF==1) 
          disp('nothing');
          k=1;
      else
          k=0;
      end
          for i=1:1:m
              if (bboxes(i,3) < 150)
                  %          display('invalid eye');
              elseif (bboxes(i,3) > 300)
                  %         display('invalid eye');
              else
                  j=j+1;
                  eye(j,:) = bboxes(i,:);
              end
          end
          if (j>0)
              for (i=1:1:j)
              if(eye(i,1)>300) && (eye(i,1)<600)
                  left_eye = eye(i,:);
                  disp('Left:');
                  disp(left_eye);
                  left_flag=1;
              elseif(eye(i,1)>600) && (eye(i,1)<900)
                      right_eye = eye(i,:);
                      disp('Right:');
                      disp(right_eye);
                      right_flag=1;
                  end
              end
   %%Movement Detection           
              if((left_flag==1)&& (prev_left_flag ==1))
                  prev_left_flag = 1;
                  if((left_eye(1,1) - prev_left(1,1))>50)
                      flag = 0;
                      display('moved left');
                  elseif  ((left_eye(1,1) - prev_left(1,1))<-50)
                      flag = 1;
                      display('moved right');
                  else
                      flag = 2;
                      display('stayed');
                      end
                  prev_left = left_eye;
              elseif((right_flag==1)&&(prev_right_flag==1))
                  prev_right_flag = 1;
                  if((right_eye(1,1) - prev_right(1,1))>50)
                      flag = 0;
                      display('moved left');
                  elseif  ((right_eye(1,1) - prev_right(1,1))<-50)
                      flag = 1;
                      display('moved right');
                  else
                      flag = 2;
                      display('stayed');
                  end
                  prev_right = right_eye;               
               elseif(left_flag==1)
                  prev_left_flag = 1;
                  if((left_eye(1,1) - prev_left(1,1))>50)
                      flag = 0;
                      display('moved left');
                  elseif  ((left_eye(1,1) - prev_left(1,1))<-50)
                      flag = 1;
                      display('moved right');
                  else
                      flag = 2;
                      display('stayed');
                  end
                  prev_left = left_eye;
              elseif(right_flag==1)
                  prev_right_flag = 1;
                  if((right_eye(1,1) - prev_right(1,1))>50)
                      flag = 0;
                      display('moved left');
                  elseif  ((right_eye(1,1) - prev_right(1,1))<-50)
                      flag = 1;
                      display('moved right');
                  else
                      flag = 2;
                      display('stayed');
                  end
                  prev_right = right_eye;               
              end
              if (left_flag == 0)
                  prev_left_flag=0;
              elseif (right_flag == 0)
                  prev_right_flag=0;
              end
      %%Motor Control Signals
              if ((prev_flag == 0) && (flag == 1)) % straight movement
                  display('motor moved straight');
                  move = 2;
                  check_straight_right = 1;
                  check_left_right = 1;
              elseif ((prev_flag ==1) && (flag == 0)) 
                  move = 2;
                  display('motor moved straight');
                  check_straight_left = 1;
                  check_right_left = 1;
              elseif ((prev_flag == 0) && (flag == 2))    % left movement
                  if ((check_right == 1) || (check_straight_right == 1)||(check_right_left))
                      move = 3;
                      display('motor stays');
                      check_right = 0;
                      check_straight_right = 0;
                      check_right_left = 0;
                  else
                      move = 0;
                      display('motor moved left');
                      check_left = 1;
                  end    
              elseif ((prev_flag == 1) && (flag == 2))   % right movement
                  if ((check_left == 1) || (check_straight_left == 1) || (check_left_right))  
                      move = 3;
                      display('motor stays'); 
                      check_left = 0;
                      check_straight_left = 0;
                      check_left_right = 0;
                  else
                      move = 1;
                      display('motor moved right');
                      check_right = 1; 
                  end
              else                                       % no movement
                  move = 3;
                  display('motor stays');
              end
              prev_flag = flag;
   %%Serial Transmission
            fprintf(s,'%1d\n',move);
              disp('done');
          end
          hold on;
      end
      stop(vid);
      flushdata(vid);
      pause(0.04);
    fclose(s);
     delete(s);
      clear s;
      clear all;

[NURUL NABILAH]

sir this is my full coding. i want change this coding by using arduino because mt project using arduino uno. but when i change serial to arduino error fopen. and motor driver cannot move.

[Walter Roberson]

Arduino can be used in two ways.

1) You could have a program ("sketch") running on the arduino that is actively reading the serial port, examining the data received, and dealing with external hardware all on its own, in a way that is hidden from the host program. That is the style that the current program is written for, where the program just sends out an encoded value of '1' (move right) or '2' (move left) or '3' (stay), and the device receiving the information is responsible for figuring out what to do what that data. If you have such a program running on the arduino, then all you should need to do is change the port number to the one that the arudino is on: you would continue to use serial() and so on. There would be almost no change to the program you show.

2) You can instead have the host program set up connections to particular hardware devices like digital pins or i2c sensors, and the host would use calls such as writeDigitalPin or writeRegister to send more direct hardware instructions as to exactly what to do at the hardware level. The program you show would have to change to set up the hardware and would have to change in how it sent hardware instructions. It is only this form of using the arduino that would use the arduino() call.

[NURUL NABILAH]

sir for the first way. i cant understand about program ("sketch"). can you explain or give me link about this.

[Walter Roberson]

https://www.arduino.cc/en/tutorial/sketch

Arduino "sketches" (programs) are written in C or C++.

You can find examples about controlling bidirectional motors. See for example http://www.instructables.com/id/Control-DC-and-stepper-motors-with-L298N-Dual-Moto/

[NURUL NABILAH]

//test for Serial COM with matlab

#define F_CPU 16000000UL

#include <inttypes.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include <stdio.h>

#include <math.h>

#include <util/delay.h>

// serial communication library

#include "uart.h"

#include "uart.c"

  double counter;

// UART file descriptor

// putchar and getchar are in uart.c

FILE uart_str = FDEV_SETUP_STREAM(uart_putchar, uart_getchar, _FDEV_SETUP_RW);

void delay (void);

void initialize(void);

int main(void)
{
  int move;  
  // 0 - left, 1- right, 2- straight, 3 - stop
  initialize();

  while(1){
       fscanf(stdin,"%d",&move); // receive data
     switch (move)
     {
       case 0:   
        PORTA = 0x01; // move left
          _delay_ms (1000); 
        break;
      
      case 1:
       
        PORTA = 0x04; // move right
          _delay_ms (1000); 
        break;
      
      case 2:
      
        PORTA = 0x05; // move straight
          _delay_ms (1000); 
        break;

      case 3:
      
        PORTA = 0x00; // halt
          _delay_ms (1000); 
        break;

      default: 
        PORTA = 0x00; // halt
          _delay_ms (1000); 
        break;

       }
}

}

void initialize(void)
{
  DDRA =0xFF;      

    //init the UART -- uart_init() is in uart.c
    uart_init();
    stdout = stdin = stderr = &uart_str;

   fprintf(stdout,"Starting...\n\r");

}

[NURUL NABILAH]

sir coding above is coding c. This coding can not be run. is this coding error?

[Walter Roberson]

The use of // as a comment delimiter requires C99 or later.

Writing to a port using something like PORTA = 0x04; would require..... ummm, I would have to research to see if it is possible at all. More typical would be *PORTA = 0x04; which is valid for memory mapped ports.

It is uncommon for motors to handle bytes of commands like that. Much more common would be pulse width modulation schemes, or rotary pulse schemes.

[NURUL NABILAH]

thank you sir. sir did you know how to compile matlab software and code block?

[Walter Roberson]

I have gone back and checked, and I find that on some systems, it is possible to write to a port using code such as PORTA = 0x04; The conditions for doing this is that the linker needs to be instructed to place the variable at a particular memory location (on a device that supports that.) See the description of scatter.txt in http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka3750.html

"did you know how to compile matlab software and code block?"

I know some things; I would prefer if you asked specific questions. Are you talking about MATLAB Compiler product (create .exe), or MATLAB Coder product (create C/C++ code), or MATLAB Compiler SDK (create .dll); or are you talking about Simulink Coder (generate C/C++ code from Simulink models); or are you talking about code generation from Simulink models for specific hardware targets such as Arduino ?

If you are trying to use MATLAB Coder to generate C/C++ code for Arduino, the task is a bit harder, as MATLAB Coder does not know anything about Arduino as a target and so has no libraries to talk to Arduino operating system or hardware -- Simulink does know about Arduino as a target.

If you want to move your entire MATLAB program onto Arduino, then you have the problem that MATLAB Coder, and Simulink, and the Support Package for Arduino, do not know how to create graphics on Arduino using imshow() or any other direct graphics. Simulink does have an Arduino video display block, which has to be sent complete images -- requiring that you do all of the drawing into an array and then send the array to be displayed as an image. The Computer Vision routines such as shape inserter and text inserter are very useful for those purposes.