designing air vending machine

Discussion in 'Homework Help' started by luckyfella, Oct 13, 2009.

  1. luckyfella

    Thread Starter New Member

    Oct 13, 2009
    This is my lab project question:

    A digital air ticket dispensing machine allocates seats for a small commercial flight. A customer can request the number of seats required. If available, the machine issues the tickets; else, the machine indicates that the requested number of seats is unavailable. The customer can then request fewer seats, if desired. Design a digital circuit to simulate a ticket dispensing machine, according to the following specifications. The machine can allocate a total of 15 seats. The number of seats required can be set on a 4-bit DIP switch and entered into the circuit by means of a pushbutton switch, ​
    REQUEST. If there are sufficient number of seats to meet the customer’s request, the machine asserts an output signal AVAILABLE from which time it takes 7 seconds to issue the tickets. The machine then asserts a signal COLLECT for T seconds (choose a convenient value for T). If the requested number of seats is unavailable, the outputsignal UNAVAILABLE is asserted for T seconds after which the customer can make a new request. The circuit can be reset by using a pushbutton switch, RESET. Use LEDs to display the status of AVAILABLE, UNAVAILABLE and COLLECT. The digital electronics laboratory has stocks of TTL integrated circuit components that are listed below. Depending on your circuit design you may need a subset of all the IC’s listed.
    You may pick the ones that you need
    after your design has been verified and approved. In addition to IC’s, you will be given a custom package containing a breadboard, a 7805 voltage regulator IC, push-button switches, 4-bit dip switches and LEDs tailored to the needs of the project assigned to you.

    the IC used are:
    -2x 74194

    i have figured out how to do the cheking of the seats availability but i'm stuck at how to light up the LED AVAILABLE for 7 sec and COLLECT for T sec as well as UNAVAILABLE for T sec. I'm quite desperate already and I need your help!! THANKS A LOT

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    It all starts with a logic diagram. Can you send us what you have?