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Homework Help: Drag Race Christmas Tree Design

  1. Nov 27, 2008 #1
    1. The problem statement, all variables and given/known data
    Question Details:
    A "Christmas Tree lighting system is used to start a drag race. The inputs to the system include a start button, a reset button, and two start line sensors. The outputs include lines for Red, Yellow, and Green lights and two Fault lights. When the operator pushes the start button, the red, yellow, and green lights turn on and then off sequentially in equal time increments. If one (or both) of the start line sensors is activated before the green lights comes on, the corresponding fault light is energized, the red, yellow and green lights go off and the system waits for a reset signal. If there is a good start, the green light remains on until the reset button is pressed.

    I need help in developing a SM (State Machine) chart for this design.

    Here's what I got. I'm pretty sure that it's incorrect though.
    SB = Start Button
    R = Reset Button
    F1 = Start Line Sensor 1
    F2 = Start Line Sensor 2

    Rd = Red Light
    Ye = Yellow Light
    Gr = Green Light
    FL1 = Fault Light 1
    FL2 = Fault Light 2

    I have attached the picture of my SM Chart that I created.

    Attached Files:

    • Soln.jpg
      File size:
      13.1 KB
  2. jcsd
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