Basically, using the 4 digit 7 segment tm1637 module and 4*4 matrix keypad.
I want to be able to type numbers on keypad, and the display will continue showing till 4th number. When I press * or #, it should clear the display. Now with the "A", "B" ,"C", "D" keys, I want a pin to pull high when I press "A" , when I press "B" pull low "A" 's pin and pull high another pin for B (4 Letters like a selector switch, to control a relay).
That’s pretty straightforward, but you’ll need to work out some of the details.
A few questions for you:
What does “displaying until the 4 th number” mean? Do you want the display to clear or lock in the number?
What should the sketch when it receives a 5th digit? It’s already displaying 4, should it ignore it or shift the displayed number, i.e., 1234 displays “1234” and pressing 5 displays “2345”?
What happens when the 4th digit is entered? Are you comparing it to an expected code or does the number get used in some other way?
I assume the A-D buttons work independently from the others and won’t intetf with the numeric sequence.