Dynamic Display in edit text box

I am integrating arduino with Matlab, which involves the use of ir sensor(TRCT 500). I am displaying the voltage read of the analog pin for ir sensor. So instead of pressing push button to get the varying outputs, i want it to be automatic. I tried with the timefcn but dont know how to apply it here.

function varargout = ir_sensor1(varargin)
% IR_SENSOR1 MATLAB code for ir_sensor1.fig
%      IR_SENSOR1, by itself, creates a new IR_SENSOR1 or raises the existing
%      singleton*.
%
%      H = IR_SENSOR1 returns the handle to a new IR_SENSOR1 or the handle to
%      the existing singleton*.
%
%      IR_SENSOR1('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in IR_SENSOR1.M with the given input arguments.
%
%      IR_SENSOR1('Property','Value',...) creates a new IR_SENSOR1 or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before ir_sensor1_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to ir_sensor1_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help ir_sensor1

% Last Modified by GUIDE v2.5 17-Oct-2022 20:59:06

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @ir_sensor1_OpeningFcn, ...
                   'gui_OutputFcn',  @ir_sensor1_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


% --- Executes just before ir_sensor1 is made visible.
function ir_sensor1_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to ir_sensor1 (see VARARGIN)

% Choose default command line output for ir_sensor1
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);



% UIWAIT makes ir_sensor1 wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = ir_sensor1_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;
clear all;
global a;
a = arduino('COM5');


% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global a;
voltage = 100*readVoltage(a,'A0');
set(handles.valtxt,'String',voltage);
if voltage <= 90
    set(handles.racetext,'String','None');
else
    set(handles.racetext,'String','No bitches');
end


function valtxt_Callback(hObject, eventdata, handles)
% hObject    handle to valtxt (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,'String') returns contents of valtxt as text
%        str2double(get(hObject,'String')) returns contents of valtxt as a double


% --- Executes during object creation, after setting all properties.
function valtxt_CreateFcn(hObject, eventdata, handles)
% hObject    handle to valtxt (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end



function racetext_Callback(hObject, eventdata, handles)
% hObject    handle to racetext (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,'String') returns contents of racetext as text
%        str2double(get(hObject,'String')) returns contents of racetext as a double

% --- Executes during object creation, after setting all properties.
function racetext_CreateFcn(hObject, eventdata, handles)
% hObject    handle to racetext (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

Answer 1

[Satyam]

Hi Brendan,

To automatically and continuously update the IR sensor reading (without pressing the button each time), a ‘timer’ object is better suited than ‘timefcn’ for GUI-based applications in MATLAB. Refer to the documentation of ‘timer’ class to know about related arguments and their syntax. https://www.mathworks.com/help//releases/R2021a/matlab/ref/timer-class.html

Here is a sample code of how we can achieve that:

Modify the ‘ir_sensor1_OpeningFcn’ function to add ‘timer’ object initialization as follows:

function ir_sensor1_OpeningFcn(hObject, eventdata, handles, varargin)
% Choose default command line output for ir_sensor1
handles.output = hObject;
% Initialize Arduino
global a;
a = arduino('COM5');  % Update port if needed
% Set up timer for automatic reading
handles.t = timer('ExecutionMode', 'fixedSpacing', ...
                  'Period', 1, ...
                  'TimerFcn', {@updateSensor, hObject});

start(handles.t);  % Start timer
% Update handles structure
guidata(hObject, handles);

‘pushbutton1_Callback’ function needs to be replaced by ‘updateSensor’ function. Here is the sample code for the same:

function updateSensor(~, ~, hObject)
    handles = guidata(hObject);
    global a;

    % Read sensor
    voltage = 100 * readVoltage(a, 'A0');

    % Update GUI text
    if isfield(handles, 'valtxt') && ishandle(handles.valtxt)
        set(handles.valtxt, 'String', voltage);
    end

    if isfield(handles, 'racetext') && ishandle(handles.racetext)
        if voltage <= 90
            %If condition
        else
            %Else condition
        end
    end
end