The on$-$board LED must blink every second, where it is on for $500ms$ and off for another

$500ms.$

At board reset, the brightness of the LED must be set to $50\%$ of its maximum brightness.

Upon pressing the user button, the brightness of the LED must increase by $20\%.$ Once

the brightness reaches $90\%,$ the following button presses should decrease the brightness

by $30\%.$ Upon reaching a brightness of $30\%,$ pressing the button should increase the

brightness by $20\%,$ and so on$.$