How do I show only an one digit in the 4 digit segment on a Basys2 board?

Question

When I used to output an one digit number in the Basys2 board, all the 4 digits glowed. eg:- When I wanted 2, it showed 2222. I want only the right most digit to work.

To achieve this, I made a ground port connected to three out puts through 3 NOT gates on the schematic file. Next I LOC that three outputs to the 3 anodes, AN1, AN2, AN3 of the board in the ucf file.

But, is there any proper way to do this?

Answer 1

You have to implement a time multiplexer.

That takes your four input digits and displays only one at a time by selecting the proper AN* signal. You should multiplex the digits > 100 Hz and < 1 kHz.