Q:

How to control time activated display update

I am looking for the method to update the screen at a constant rate, say every 50mSec. 
In the embedded world I would configure a timer to trigger an interrupt every 50mSec and the ISR would handle the update.  What I have in mind for Android is to have a FrameLayout with a number of view items registered to react to some sort of callback from a timer function. 
Hopefully someone will understand my question and point me in the right direction. 

A:

You may use handler.postDelayed in a Runnable to call it after certain time period. 
For example:
    handler.post(new Runnable() {

        @Override
        public void run() {
            handler.postDelayed(this, 50);
            //do your task
        }
    });

Make sure you handler is attached to a separate (non-UI) thread and when it comes to update UI elements you always do it on a UI thread.