Traffic Light Controls

Discussion in 'Homework Help' started by bjerkset, Nov 23, 2009.

  1. bjerkset

    Thread Starter New Member

    Nov 8, 2009
    5
    0
    Hello everyone.

    I am trying to design a circuit that operates a traffic control system at the intersection of a primary and secondary highway. The conditions for the operation of the control system are specified below.


    1.
    If no vehicle is detected on the secondary road, the highway lights should be green, while the secondary road lights should be red.

    2.
    If a vehicle is detected on the secondary road, the change signal will be asserted and the highway lights should cycle through yellow, then red. The secondary road lights will then turn green.

    3.
    The secondary road lights will remain green so long as a vehicle is detected on the secondary road.

    4.
    When no further cars are detected on the secondary road, the light should cycle from yellow to red. The highway light will then turn green.

    5.
    If an emergency vehicle is detected on the primary highway at any time, the EMV signal will be asserted and the highway lights should immediately (next clock cycle) switch to green, while the secondary road lights should turn red.


    Based on the description i think that it will have to be implimented using 2 D flip flops and some type of memory elements.

    So far I have come up with a state table i would like to use but I am lost as to where to go from this point, mainly because in class we have only analysied circuits and have yet to design them.

    My state table is attached

    Help is greatly thanked, oh its important to note in the attached state table the presence of the !(not) operator in some places, its kind of hard to see.

    I will continue to work on it and hope to hear from you guys soon
     
    Last edited: Nov 23, 2009
  2. bjerkset

    Thread Starter New Member

    Nov 8, 2009
    5
    0
    help... anyone?
     
  3. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    Try giving more than 3 hours for a reply, not everyone has time to camp out on the forums.
    For your question though:
    Are you required to use any specific parts?
    It's been a while since I've done any state machines, but I would think this would use JK flip flops with all the CLKs tied together.

    This might be of some use to you.
    http://www.scribd.com/doc/22638524/Publish-Traffic-Signal-Logic-Controller
     
  4. bjerkset

    Thread Starter New Member

    Nov 8, 2009
    5
    0
    It is asked that we make use of D flip flops instead of JK flip flops. So far we have covered how the analysis of state machines, but this requires me to do the reverse i guess. Any insight as to where i should go from the state table/next state chart?
     
    Last edited: Nov 24, 2009
  5. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    Here is a way to go about designing state machines:
    http://meseec.ce.rit.edu/eecc341-winter2001/341-2-7-2002.pdf

    I'm assuming you have already made the state/next state table.
    It's been a long time for me, so I am refreshing myself on this as I go. Hopefully someone else can pitch in... I will post more when I have more time to work on this.
     
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