MATLAB: How to Create RT clock in the own GUI

guirt clocktimer

Hello,
I have the following code (it's upon GUI creation):
set(handles.time_caption,'String',datestr(now,13))
tmr = timer('Name','Reminder',                   ...
            'Period',1,                          ...  % Update the time every 1 seconds.
            'StartDelay',0,                      ...  % In seconds.
            'TasksToExecute',inf,                ...  % number of times to update
            'ExecutionMode','fixedSpacing',      ...
            'TimerFcn',{@updater_mg}); 
start(tmr);                                           % Start the timer object.
function [] = updater_mg(varargin)
    set(handles.time_caption , 'string' , datestr(now,13))
end
I receive the following error:
Error while evaluating TimerFcn for timer 'Reminder' 
Undefined variable "handles" or class "handles.time_caption".
I understand that when I'm "inside" the updater_mg function it doesn't recognize my handles struct from a layer above.
How can I overcome this?

Best Answer

If handles is unknown in the callback, provide it as input:
set(handles.time_caption,'String',datestr(now,13))
tmr = timer('Name','Reminder',                   ...
          'Period',1,                          ...  % Update the time every 1 seconds.
          'StartDelay',0,                      ...  % In seconds.
          'TasksToExecute',inf,                ...  % number of times to update
          'ExecutionMode','fixedSpacing',      ...
          'TimerFcn',{@updater_mg, handles});     % <== HERE
function updater_mg(TimerH, EventData, handles)   % <== AND HERE

  set(handles.time_caption , 'string' , datestr(now,13));
end
Add a security check:
function updater_mg(TimerH, EventData, handles)   % <== AND HERE
  if ishandle(handles.time_caption)
    set(handles.time_caption , 'string' , datestr(now,13));
  else
    disp('Timer for clock stopped: GUI was closed');
    stop(TimerH);
  end
end
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