Hello everyone,
I need help designing a 4 traffic light controller for my graudation project, right now I chose to use the decade counter ic 4017 but I have no clue on how to create a cascade connection with other counters while keeping the Red light on for others...
your help is greatly appreciated...
If you're attempting to use multiple 4017s and try to hold one or more off while another is counting, you'll need 'glue' logic, so it would be easier to just build a 'state generator' with one counter and logic.
If you look at the functions of a 'simple' intersection (N/S E/W red yellow green, no left turns), then you can do this with just one counter. The apparent states are:
1) N/S go, E/W stop approx 30 seconds... counts 10
2) N/S yel, E/W stop approx 6 seconds... counts 2
3) All Stop... approx 3 seconds.... counts 1
4) E/W go, N/S stop approx 30 seconds... counts 10
5) E/W yel, N/S stop approx 6 seconds... counts 2
6) All Stop... approx 3 seconds.... counts 1
The counts are based on the ratio of the smallest unit (all stop) to the largest unit (go).
The 'state' logic can be done with (1) 4017 decade counter/decoder, (1) quad nand, (1) hex inverter (scmidt trigger), (1) quad OR, and (2) Dual D f/fs.
Inputs to the circuit: 1/3 Hz clock, Power on Reset signal.
This will yield the following signals: E/W, N/S (-E/W), YEL, -YEL, ALL (all stop), -ALL.
There will be some additional logic to turn on the outputs from the above signals (decode the above signals to determine which outputs to turn on. Either some nands, nors, ands, ors or (2) octal decoder chips (like the 74c138).
Let me know if this is the path you want to take, and I'll continue to help you develop the schematic.