just give space for a sense of personal reusable code

Your first post suggested that the OP used non-personal code (why else would there be code in your post) which I replied to,

I do, of course, often use code I wrote before.

The point I made was - and I stick to it - that using non-personal code (i.e. replacing understanding with downloaded code) is a recipe for disaster.

Erik

By the way, the code you present is horrible, polled serial???? what is wrong with ISRs. Polled serial will make every time dependent issue go to hell