How to make Arduino runs continuous routines even inside a "switch case loop".

PeterH:

8bit_Biker:
Is it a correct way adding "ch=0;" inside a case to get only a value from the selected case?

That will cause the corresponding function to get called once when the command was received, and not run again until the command was sent again. If I understood your original post correctly, that's not what you wanted.

Hi PeterH!
What I wrote above is very useful to me to get the function returns only one value instead of multiple values (that's what I need to obtain from "Pres()" function).
Another time thank you very very much for you help! Really useful to me!