Need help creating Traffic Light Controller

Discussion in 'Homework Help' started by Laldin, May 28, 2015.

  1. Laldin

    Thread Starter New Member

    May 28, 2015
    Hi, first time posting here. I need help with my assignment. My assignment is to create Traffic Light Controller that has lights cycle through Red-Yellow-Green continuously. The design is made of two sub-systems that work as follows:
    3-bit Asynchronous Counter that continuously counts from 1-6
    The Combinational Logic Encoder takes the count from the 3-bit Asynchronous Counter and drives the Red, Yellow and Green lights as follows:
    -The Red light will be on when the count equals 1 or 2
    -The Yellow light will be on when the count equals 3 or 4
    -The Green light will be on when the count equals 5 or 6

    Design Specifications:
    Combinational Logic Encoder needs to include K-Map for each output (Red, Yellow and Green)
    The logic for the RED output may only use 2-Input NOR gates
    The logic for the YELLOW output may only use 2-Input NAND gates
    The logic for the GREEN output may only use 2-Input AND, 2-Input OR and Logic Inverters

    I already got the first part, which is creating the circuit that counts from 1-6. Here's what I need help on: I don't know how to start the K-Map and I don't know how to create the Combinational Logic Encoder. Also, the software we're using to create this is Multisim.Thank you.
  2. MrCarlos

    Active Member

    Jan 2, 2010
    Hello Laldin

    I think the first thing to start your K-Map is studying.

    If you want to learn the seven rules of simplification (K-Map's) you can see the video below:
    Or if you want to learn the characteristics of the Karnaugh Map you can see the video below:
    If you look at the video below you will see that you have to learn, too, the Gray code.
    There are plenty of videos through WEB. You can use the search engine to find them.
    Practically in all languages.

    From what you mention in your original message, there are three variables:
    R (ed).
    Y (ellow). -Actually this color is amber-.
    G (reen).
    Reading the = sign as if
    Reading the + sign as or
    we find that:
    R = 1 + 2.
    Y = 3 + 4.
    G = 5 + 6.
    The variables R, Y, G are very similar to the previous watching videos. . . Right??
    So I think, you can already start your Karnaugh maps.

    Now, I'd like to see your design counter, 1-6. As you mention you have developed with the Multisim simulator but not mention what version you use.
    If you use any version 10, 11 or 12, please compress the file, generated with the simulator, through WinZip or WinRAR and upload here.
    If you want you can also upload an image with the intention that someone will suggest a possible improvement to your design.