Passing arguments into timer stopFCN in gui

Hello all,

I'm having a little confusion on using a timer in data acquisition GUI. I was hoping someone could give me a little help with the syntax. Basically I have code that acquires data and looks like this

function acquireButton_Callback(hObject, eventdata, handles)

sweepsPerTrigger = str2double(get(handles.editSweepsPerTrig, 'String'));
inter_stimulus_interval = str2double(get(handles.editISI, 'String'));

acquisitionTimer = timer;
acquisitionTimer.ExecutionMode = 'fixedRate';
acquisitionTimer.TasksToExecute = sweepsPerTrigger;
acquisitionTimer.Period = inter_stimulus_interval;
acquisitionTimer.StopFcn = @acquisitionTimerCleanup; %(acquisitionTimer, hObject, eventdata, handles);
acquisitionTimer.TimerFcn = @(myTimerObj, thisEvent)startAcquisition(hObject, eventdata, handles);
start(acquisitionTimer);

function acquisitionTimerCleanup(acquisitionTimer,~)
disp('Done Acquiring');
delete(acquisitionTimer);
set(handles.acquireButton, 'String', 'Acquire');
set(handles.acquireButton, 'BackgroundColor', 'g');

The issue that I have is that the stopFCN cannot access the handles.acquireButton to change the string and background color. How do I go about passing "hObject, eventdata, handles" to the stopFCN so that it can modify them.

Thank you tremendously for the help. Quentin

Answer 1

[Quentin]

Thanks Walter. I got an error message when I tried this. It said "Error while evaluating StopFcn for timer 'timer-1'. I'm assuming I need to modify the line

function acquisitionTimerCleanup(acquisitionTimer,~)

Is that correct? I'm not exactly what the ~ means in this case. Also was wondering if you describe why you used the @(src, evt) . I've never quite been able to figure out what the @ symbol means in these callback functions.

Thanks Walter.

[Walter Roberson]

function acquisitionTimerCleanup(acquisitionTimer, evt, handles)

For the @ syntax see http://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

Answer 2

[Walter Roberson]

Provided that all you need is the button handles and they are not going to change after you configure the timer, then:

acquisitionTimer.StopFcn = @(src, evt) acquisitionTimerCleanup(src, evt, handles);

If you make any changes to the handles structure between the time that you configure the timer and the time the stop function runs, then the above will not work.