Error while evaluating TimerFcn for timer 'timer-1' SIZE must be greater than 0.

I have done a project to measure heart rate by BPM for 2 months. I created an interface in computer by GUIDE MATLAB. Actually, I got the source code about getting data UART from another and I re-coded it. However, when MATLAB does not notice errors, but it shows this sentence :

    Error while evaluating TimerFcn for timer 'timer-1' 
    SIZE must be greater than 0.

Can anyone know to solve this problems. Thanks a lot.

This is my code to get data UART :

            function btn1_Callback(hObject, eventdata, handles)
            % hObject    handle to btn1 (see GCBO)
            % eventdata  reserved - to be defined in a future version of MATLAB
            % handles    structure with handles and user data (see GUIDATA)
            set(handles.btn1,'Enable','off');
            set(handles.btn2,'Enable','on');
            set(handles.Comport,'Enable','off');
            set(handles.Baudrate,'Enable','off');
            set(handles.start_togglebutton,'Enable','on');
            set(handles.PB_Exit,'Enable','on');

            global s;
            global t;
            portList = get(handles.Comport,'String');
            portIndex = get(handles.Comport,'Value');
            port = portList(portIndex,:);
            set(s,'Port',char(port));

            brList = get(handles.Baudrate,'String');
            brIndex = get(handles.Baudrate,'Value');
            br = char(brList(brIndex,:));
            br = str2num(br);
            set(s,'Baudrate',br);

            % fopen(s);
            if strcmp(get(hObject,'String'),'Connect')
                assignin('base', 't0', 0); % t?o trong workspace t0=0 đ? chu?n b? làm data m?i

            s = serial(get_stringPopup(handles.Comport));
            s.InputBufferSize = 20000;
            s.Baudrate = br;
            s.DataBits = 8;
            s.Parity = 'none';
            s.StopBit = 1;
            s.BytesAvailableFcnCount = 1000;
            s.BytesAvailableFcnMode = 'terminator';

            try
                handles.s = s;
                fopen(handles.s);
                pause(0.2);
                delete(timerfindall);
                TMR_PERIOD = 0.5;
                t = timer('TimerFcn',@(x,y)getDataUART(s),'Period',TMR_PERIOD);
               set(t,'ExecutionMode','fixedRate');
                start(t);
            catch e
                if(strcmp(s.Status,'Open'))
                    fclose(handles.s);
                end
                errordlg(e.message); %x? l? ngoài l?, n?u không có ngoài l? x?y ra th? s? th?c hi?n catch
            end
            else
                set(hOject,'String','Connect')
                fclose(handles.s);
                stop(t);
            end

            guidata(hObject,handles);

            function getDataUART(s)
            load handles
            persistent nPts;
            persistent xTime;
            persistent yDataCH1;
            global b, global start,
            data = fread(s,s.BytesAvailable);
            % Data
            fNaN=find(isnan(data)==1); % mang chua vi tri phan tu NaN
            if (~isempty(fNaN))
            for i=1:length(fNaN)%lenLaser %length(fNaN)
            data(fNaN(i))=0;
            end
            end
            % lay t0 de ve va lam dieu kien reset
            t0 = evalin('base', 't0'); % doc bien tu workspace
            % Initial variable
            if (t0==0)
            nPts = 5000; % number of points to display on stripchart
            xTime = ones(1,nPts)*NaN;
            yDataCH1 = ones(1,nPts)*NaN;
            end
            % length
            lenFrameData=length(data);
            % Creat Data
            nDataCH1 = [];
            % Control Data
            synIndex = 1;
            % uint8_t UART_Header[5] = {0xFF,0x00}; // ky tu dac biet
            while (synIndex < (lenFrameData - 5))
            if ((data(synIndex)==255)&&(data(synIndex+1)==0))
            nDataCH1 = [nDataCH1 (data(synIndex+3)*256+data(synIndex+2))]; % IR truoc
            synIndex = synIndex + 6; % bo qua khung vua roi
            else
            synIndex = synIndex + 1; % do dong bo
            end
            end

            % Real Data Bases
            lenData = length(nDataCH1);
            % Update the plot, initial t0=0 in workspace
            % t1=length(TimeSecond);
            time = t0:1:t0+lenData-1;
            t0 = t0+lenData-1; % update th?i đi?m lúc sau
            assignin('base', 't0', t0); 

            % fix up data to change plot
            xTime(1:end-lenData) = xTime(lenData+1:end); % shift old data left
            xTime(end-lenData+1:end) = time; % new data goes on right
            % channel 1
            global HeartCountReal, global timecount
            yDataCH1(1:end-lenData) = yDataCH1(lenData+1:end); % shift old data left
            yDataCH1(end-lenData+1:end) = 0 + 1*nDataCH1*5/1023;
            output=yDataCH1;
            output1=filter(b,1,output);
            heart_processed1=output1(1,end-49:end).^2;
            check1=size(find(heart_processed1>1.56),2);
            timecount=timecount+1;
            if check1>0
            HeartCountReal=HeartCountReal+1;
            end
            % HeartCountReal
            % timecount

            if timecount==120;
            set(handles.bpm_edit,'string',num2str(HeartCountReal))
            if HeartCountReal <60
            set(handles.heartStatus_text,'string','LOW');
            elseif HeartCountReal<=100
            set(handles.heartStatus_text,'string','NORMAL');
            else
            set(handles.heartStatus_text,'string','HIGH');
            end
            HeartCountReal=0;
            timecount=0;
            end
            global timelength,global strengthEx,global save_exper, global save_heart,global heart_count,global countdown
            if start==1
            save_heart=[save_heart output1(1,end-49:end)];
            assignin('base', 'save_heart', save_heart)
            out1=output1(1,end-49:end).^2;
            S=size(find(out1>1.7),2);
            if S>0
            heart_count=heart_count+1;
            end
            timelength=timelength+1;
            if rem(timelength,2)==0
                countdown= countdown-1;
            set(handles.countdown_text,'string',[num2str(countdown) ' s'])
            end
            if timelength==30
            start=0;
            set(handles.start_togglebutton,'value',0);
            HeartRate=heart_count*4;
            set(handles.hr_text,'string',[num2str(HeartRate) ' BPM']);
            if HeartRate <60
            set(handles.hb_text,'string','LOW');
            elseif HeartRate<=100
            set(handles.hb_text,'string','NORMAL');
            else
            set(handles.hb_text,'string','HIGH');
            end
            save_exper=[save_exper strengthEx];
            assignin('base', 'save_exper', save_exper)
            heart_count=0;
            end
            end
            assignin('base', 'yDataCH1', yDataCH1); % tao trong workspace
            assignin('base', 'xTime', xTime); % tao trong workspace
            xmax=max(xTime);
            % plot in MATLAB
            set(handles.axes3,'NextPlot','add'); % lenh hold on trong GUI
            grid(handles.axes3, 'on');
            % plot(handles.axes1,xTime,yDataCH1,'r-','LineWidth',2) ;
            plot(handles.axes3,xTime,output1,'r-','LineWidth',2) ;
            title(handles.axes3,'OXY SATURATION OF FINGER 1')
            axis(handles.axes3,[xmax-400 xmax 0 7]);
            save('handles.mat', 'handles');

            function doublePopup = get_doublePopup(hObject,handles)
            val = get(hObject,'Value');
            string_list = get(hObject,'String');
            selected_string = string_list{val}; % convert from cell array
            % to string
            doublePopup = str2double(selected_string);
            % Function to
            function stringPopup = get_stringPopup(hObject,handles)
            val = get(hObject,'Value');
            string_list = get(hObject,'String');
            stringPopup = string_list{val}; % convert from cell array

[Jan]

Please post the complete error message and do not let use guess the line, which causes the error.

load handles loads the file handles.mat from the hard disk. It is very inefficient to do this twice a second.

A hint:

fNaN = find(isnan(data)==1); % mang chua vi tri phan tu NaN
if (~isempty(fNaN))
  for i=1:length(fNaN)%lenLaser %length(fNaN)
     data(fNaN(i))=0;
  end
end

Nicer, faster and simpler:

data(isnan(data)) = 0;

Answer 1

[Naman Gupta]

Similar problem.