Build a running LED light logic circuit

manpreet Best Answer 3 years ago

I am a beginner at logic gates/circuits and would appreciate some help constructing a running LED light system. The concept is to have a row of 20 LED lights that start flashing, one after another, after receiving a certain input. The only two options are for the rightmost LED to light up and then go left, or for the leftmost LED to light up and go right. Only one light will be on at a time, and each light will stay on for 5ms.

The system takes a 2-bit input, where "l" means "left" and "r" means "right:
l r
0 0 -- "Off" (see below)
0 1 -- start at leftmost and run right
1 0 -- start at rightmost and run left
1 1 -- "Off" (see below)

There is also a 5-bit number can turn on one LED at a time, or be set to "Off":
00000 -- "Off"
00001 -- L0 (leftmost LED)
00010 -- L1
00011 -- L2
...
...
...
10010 -- L17
10011 -- L18
10100 -- L19 (rightmost LED)

This is essentially as far as I've gotten, apart from making a finite state machine that describes what I said in the beginning. I'm only interested in using logic gates at this point. I would just appreciate a push forward so I know where to start with this. I know I'll need to be using a D flip-flop. Thank you for any help you can provide.