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Problems with while. The program is blocked

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Guillermo Cid Espinosa
Guillermo Cid Espinosa on 30 Oct 2017
Closed: MATLAB Answer Bot on 20 Aug 2021
I'm doing a graphical interface with app designer and I want a function to run while a condition is fulfilled but the problem is that the while is not executed and the application is blocked.
Guillermo Cid Espinosa
Guillermo Cid Espinosa on 8 Nov 2017
If I run the program the application is blocked. I can not activate any of the functions programmed in the app or close it. I need to press ctrl + Alt + Sup to close matlab. On the other hand I have seen in the workspace that several data packages are received although these are not represented in the graph so app.Button.Value is equal to one. So it seems that the while is running now but I can not get the data to appear in the graph.
The main problem is that it always receives the same data (several times while the button is connected) only if I go back to disconnect and connect the PtButton receives new data

Answers (1)

Guillaume on 8 Nov 2017
Disclaimer: I've never used the app designer. Maybe mathworks have changed how things work compared to the 'old' gui tools.
Matlab is single threaded. That means it can only do one thing at once. Therefore, when it is executing a loop, it's not going to respond to user events. Therefore, once your code has entered your loop it's going to look like the app is frozen as you never give a chance to matlab to check that your ptButton has changed state.
The fix for that is normally to insert a drawnow in your loop. drawnow tells matlab to actually update figures (without it, you won't see the changes made by your plot) and process the user events such as button clicks.
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Guillermo Cid Espinosa
Guillermo Cid Espinosa on 15 Nov 2017
Thanks for answering. But the problem is that the data received from the micro is not updated despite the function fprintf. The most data are always received and displayed.

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