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1

Sending values from Matlab to arduino using serial communication

Asked by Naseeb Gill on 18 Feb 2017
Latest activity Commented on by Walter Roberson
on 20 Nov 2019 at 0:42
I want to send numeric value from matlab to arduino but code is not working. Matlab code is as:
doi = 3 ;
arduino=serial('COM5','BaudRate',9600); % create serial communication object
fopen(arduino); % initiate arduino communication
fprintf(arduino, '%s', char(doi)); % send answer variable content to arduino
fclose(arduino);
Arduino code is as:
int solenoidPin = 13; //This is the output pin on the Arduino
int doi;
void setup()
{
Serial.begin(9600);
//pinMode(13, OUTPUT);
pinMode(solenoidPin, OUTPUT); //Sets that pin as an output
}
void loop()
{
if(Serial.available()>0)
{
doi = Serial.read();
//Serial.println(doi);
//Serial.println("\n");
//doi = doi - 48;
if (doi == 1)
{
//Serial.println(1);
digitalWrite(solenoidPin, HIGH); //Switch Solenoid ON
delay(1000); //Wait .15 Second
digitalWrite(solenoidPin, LOW);
}
else if (doi == 2)
{
//Serial.println(2);
digitalWrite(solenoidPin, HIGH); //Switch Solenoid OFF
delay(2000); //Wait .165 Second
digitalWrite(solenoidPin, LOW);
}
else
{
//Serial.println(3);
digitalWrite(solenoidPin, HIGH); //Switch Solenoid OFF
delay(3000); //Wait .180 Second
digitalWrite(solenoidPin, LOW);
}
}
}
I used str2num(doi) also instead of fprintf(arduino, '%s', char(doi)) but no output.
Please give suggestion to correct this.
Thanks.

  5 Comments

how do you know that it takes 2 sec to open?
how to print the values send from matlab to arduino??
There are a few possibilities for display:

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3 Answers

Answer by Walter Roberson
on 21 Feb 2017

"But what the problem is I do not know how to use _fopen(arduino) command between functions in GUI?"
fopen once and save the object somewhere so that you do not need to fopen again.

  1 Comment

I already tried handles as you suggested as below:
function varargout = exam(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', @exam_OpeningFcn, ...
'gui_OutputFcn', @exam_OutputFcn, ...
'gui_LayoutFcn', [] , ...
'gui_Callback', []);
if nargin && ischar(varargin{1})
gui_State.gui_Callback = str2func(varargin{1});
end
if nargout
[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT
function exam_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% --- Outputs from this function are returned to the command line.
function varargout = exam_OutputFcn(hObject, eventdata, handles)
varargout{1} = handles.output;
function edit1_Callback(hObject, eventdata, handles)
% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
% --- Executes on button press in pushbutton1.
% pushbutton to create serial communication between matlab and arduino
function pushbutton1_Callback(hObject, eventdata, handles)
arduino=serial('COM5','BaudRate',9600); % create serial communication object on port COM4
fopen(arduino); % initiate arduino communication
pause(2);
handles.arduino = arduino;
guidata(hObject,handles);
% --- Executes on button press in pushbutton2.
% After enter value in edit box press pushutton to send data to arduino
function pushbutton2_Callback(hObject, eventdata, handles)
ard = handles.arduino;
number = str2num(char(get(handles.edit1,'String')));
fprintf(ard, '%i', number);
guidata(hObject,handles);
% --- Executes on button press in pushbutton3.
% to clear the port and close arduino communication
function pushbutton3_Callback(hObject, eventdata, handles)
fclose(handles.arduino);
delete(instrfind({'Port'},{'COM5'}));
guidata(hObject,handles);
But arduino is not working. It just blink once when I gave input through edit box. And it is not showing any error too. Can you suggest me the solution by seeing above matlab GUI code. Thanks.

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Answer by Rouis Jihene on 31 May 2017

Hello, i tried the code but i don't get the value (doi) in arduino ! why? please help

  3 Comments

On the arduino side, you are probably trying to read the data as text instead of as binary. The replacement for
fprintf(arduino, '%s', char(doi)); % send answer variable content to arduino
should be
fprintf(arduino, '%d\n', doi); % send answer variable content to arduino
Hello Mr Walter Roberson, even i use the instruction that you told me but i doesn't work ! please help
Sorry, I do not have an arduino to test with.

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Answer by Azrg
on 23 Oct 2019

The thing you want to send has to be in a while loop like
while true
fprint(something);
end
Because Matlab has to keep trying to send the information until Arduino receives it.

  0 Comments

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