Programming and Data Types

Creating and Deleting Timer Objects

To use a timer in MATLAB, you must create a timer object. The timer object represents the timer in MATLAB, supporting various properties and functions that control its behavior.

To create a timer object, use the timer function. You can create a timer object with default attributes and then use the set function to specify the values of its properties, as in this example:

• t = timer;
  set(t,'TimerFcn','disp(''Hello World!'')','StartDelay',15)
  

You can also set timer object properties when you create the timer object by specifying property name and property value pairs as arguments to the timer function:

• t = timer('TimerFcn', 'disp(''Hello World!'')','StartDelay',15);
  

Deleting Timer Objects from Memory

When you are finished with a timer, delete it from memory using the delete function:

• delete(t)
  

When you delete a timer object, workspace variables that referenced the object remain. Deleted timer objects are invalid and cannot be reused. Use the clear command to remove workspace variables that reference deleted timer objects. To test if a timer object has been deleted, use the isvalid function. The isvalid function returns false for deleted timer objects:

• isvalid(t)
  ans =
  
       0
  

To remove all timer objects from memory, enter

• delete(timerfind)
  

See Finding All Timer Objects Currently in Memory for information about the timerfind function.

Finding All Timer Objects Currently in Memory

To find all the timers that are currently in memory, use the timerfind function. This function returns an array of timer objects. If you leave off the semicolon, and there are multiple timer objects in the array, timerfind displays summary information in a table:

• t = timer;
  t2 = timer;
  t3 = timer;
  t_array = timerfind
  
  Timer Object Array
  
     Index:  ExecutionMode:  Period:  TimerFcn:    Name:
     1       singleShot      1        ''           timer-3
     2       singleShot      1        ''           timer-4
     3       singleShot      1        ''           timer-5
  

MATLAB assigns a name to each timer object you create. This name has the form 'timer-i', where i is a number representing the total number of timer objects created this session. In this example, the list of timer object names start with timer-3. This indicates that two other timer objects were previously created and then deleted in this MATLAB session. If you issue the clear classes command, MATLAB resets i to 1.

Using MATLAB Timers

Timer Object Properties