My matlab while loop isn't recognising my function button press - matlab

Question

I have a script that runs when a button is pressed causing a while loop to initiate. When my stop button is pressed it is supposed to cause the loop condition to be untrue thus stopping the loop. My stop button doesn't seem to stop the loop during testing. it would seem the value I assigned in the pushDisconnect button isn't updating to the while loop and i'm not sure why this is occurring.
% --- Executes on button press in pushConnect.
function pushConnect_Callback(hObject, eventdata, handles)
% hObject handle to pushConnect (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushDisconnect,'Enable','on')
set(handles.pushConnect,'Enable','off')
handles.myDevice.StartAcquisition;
sampleRate_BP = double(handles.myDevice.BioPotentialSignals.SamplesPerSecond);
axis_handles = zeros(1,handles.numEnabledBPChannels);
BioPotentialSignals = cell(1,handles.numEnabledBPChannels);
handles.CheckFinger = cell(1,5);
handles.stopNow = 0;
for ch = 1:handles.numEnabledBPChannels
axis_handles(ch) = subplot(length(axis_handles),1,ch,'Parent',handles.uipanelGraph);
if ch==1
title(char(handles.deviceName))
end
ylabel([char(handles.myDevice.BioPotentialSignals.Item(ch-1).Name) ' (V)']);
hold on
end
xlabel('Time (s)')
linkaxes(axis_handles,'x')
plotWindow = 5;
plotGain_BP = 1;
while handles.stopNow == 0
for ch = 1:handles.numEnabledBPChannels
BioPotentialSignals{ch} = [BioPotentialSignals{ch};handles.myDevice.BioPotentialSignals.Item(ch-1).GetScaledValueArray.double'];
if length(BioPotentialSignals{ch}) <= plotWindow*sampleRate_BP
cla(axis_handles(ch))
t = (0:(length(BioPotentialSignals{ch})-1))*(1/sampleRate_BP);
plot(axis_handles(ch),t,plotGain_BP*BioPotentialSignals{ch});
xlim([0 plotWindow])
else
if ch==1
t = ((length(BioPotentialSignals{ch})-(plotWindow*sampleRate_BP-1)):length(BioPotentialSignals{ch}))*(1/sampleRate_BP);
end
cla(axis_handles(ch))
plot(axis_handles(ch),t,plotGain_BP*BioPotentialSignals{ch}(end-plotWindow*sampleRate_BP+1:end));
xlim([t(end)-plotWindow t(end)])
end
end
% Update handles structure
guidata(hObject, handles);
pause(0.1)
disp(handles.stopNow)
end
% Stop signal
handles.myDevice.StopAcquisition;
% Disconnect from all sensors
handles.myDevice.Disconnect;
msgbox('Device requires cycling, in order to restablish connection. Closing program.')
% Close window
close all;
% --- Executes on button press in pushDisconnect.
function pushDisconnect_Callback(hObject, eventdata, handles)
% hObject handle to pushDisconnect (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushDisconnect,'Enable','off')
handles.stopNow = 1;
% Update handles structure
guidata(hObject, handles);
Final Working Code, if anyone is interested:
% --- Executes on button press in pushConnect.
function pushConnect_Callback(hObject, eventdata, handles)
% hObject handle to pushConnect (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushDisconnect,'Enable','on')
set(handles.pushConnect,'Enable','off')
handles.myDevice.StartAcquisition;
sampleRate_BP = double(handles.myDevice.BioPotentialSignals.SamplesPerSecond);
axis_handles = zeros(1,handles.numEnabledBPChannels);
BioPotentialSignals = cell(1,handles.numEnabledBPChannels);
handles.CheckFinger = cell(1,5);
handles.stopNow = 0;
for ch = 1:handles.numEnabledBPChannels
axis_handles(ch) = subplot(length(axis_handles),1,ch,'Parent',handles.uipanelGraph);
if ch==1
title(char(handles.deviceName))
end
ylabel([char(handles.myDevice.BioPotentialSignals.Item(ch-1).Name) ' (V)']);
hold on
end
xlabel('Time (s)')
linkaxes(axis_handles,'x')
plotWindow = 5;
plotGain_BP = 1;
% Update handles structure
guidata(hObject, handles);
while handles.stopNow == 0
for ch = 1:handles.numEnabledBPChannels
BioPotentialSignals{ch} = [BioPotentialSignals{ch};handles.myDevice.BioPotentialSignals.Item(ch-1).GetScaledValueArray.double'];
if length(BioPotentialSignals{ch}) <= plotWindow*sampleRate_BP
cla(axis_handles(ch))
t = (0:(length(BioPotentialSignals{ch})-1))*(1/sampleRate_BP);
plot(axis_handles(ch),t,plotGain_BP*BioPotentialSignals{ch});
xlim([0 plotWindow])
else
if ch==1
t = ((length(BioPotentialSignals{ch})-(plotWindow*sampleRate_BP-1)):length(BioPotentialSignals{ch}))*(1/sampleRate_BP);
end
cla(axis_handles(ch))
plot(axis_handles(ch),t,plotGain_BP*BioPotentialSignals{ch}(end-plotWindow*sampleRate_BP+1:end));
xlim([t(end)-plotWindow t(end)])
end
end
handles = guidata(hObject);
drawnow
pause(0.1)
end
% Stop signal
handles.myDevice.StopAcquisition;
% Disconnect from all sensors
handles.myDevice.Disconnect;
msgbox('Device requires cycling, in order to restablish connection. Closing program.')
% Close window
close all;
% --- Executes on button press in pushDisconnect.
function pushDisconnect_Callback(hObject, eventdata, handles)
% hObject handle to pushDisconnect (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushDisconnect,'Enable','off')
handles.stopNow = 1;
% Update handles structure
guidata(hObject, handles);

Answer 1

Kill the guidata(hObject, handles) line, and replace it by handles=guidata(hObject) since you're overwriting the GUI state with whatever was current at the time the loop started, and you want to be polling the GUI state instead. Put the guidata(hObject, handles)-line before the loop, to ensure that handles.stopNow is indeed reset to 0.
If that doesn't help, an additional problem may be that Matlab waits with processing commands from one button callback until the other callback is done running.
Two things you can try: Add a drawnow command before the pause. This will force the GUI to update, and processes all the interactions. Also, make sure that the pushbutton callback for pushConnect is interruptible.