How can I run a stopwatch in MATLAB and store time points in a variable by hitting a key on the keyboard?

I am collecting a continuous recording from a sensor, but I will only need certain segments of the recording. I want to use a stopwatch in MATLAB to record the start and stop times of the relevant segments of data from the sensor. I need a function that starts a timer when I push one key, then stores the timer value when I press another key and that stops the timer when I press a third key. I was going to use the tic and toc functions . . . how do I get MATLAB to store the time elapsed since the last tic when I hit a certain key on the keyboard? Thanks!

[Ngonidzashe Nedziwe]

i would suggest reading through this previous post https://www.mathworks.com/matlabcentral/answers/262561-i-d-like-to-make-a-timer-or-stopwatch

Answer 1

[Abhinav Gurram]

As you rightly mentioned, the use of ' tic ' and ' toc ' functions seem best suited for your workflow. You can use any of the ways listed here: Ways to build apps to build an app, and have corresponding buttons for starting(tic) and stopping(toc) the timer. Furthermore, the 'tic' function can be used along with a variable to record time for simultaneous time spans. The variable, 'timerVal', has a value that is equal to the value of the internal timer at the execution of the 'tic' command. The 'tic' function can now be called as:

>>timerVal = tic

Afterward, you can use the 'toc' function to capture the elapsed time since the 'tic' command corresponding to 'timerVal' as:

>>elapsedTime = toc(timerVal);

You can associate the variable, 'elapsedTime' with a particular callback function that is executed when a keyboard key is pressed. The 'KeyPressFcn' might be a good way to capture the user's keyboard input. You can visit the following link for more information on how to write callbacks for apps:

1. Write Callbacks for Apps Created Programmatically
2. Write Callbacks in GUIDE

Hope this helps!