Vending Machine Circuit

Discussion in 'Homework Help' started by Netmaxweb, Sep 27, 2012.

  1. Netmaxweb

    Thread Starter New Member

    Sep 26, 2012
    Hello All About Circuits,

    I have a logic circuit design project, which I am having trouble assembling…ultimately it is going to need to be designed using the application called Xilinx ISE. This application is free but takes up 16 GB of space on my machine. But first I need to understand more about how to arrange the circuit.

    I have to build the core processing unit of a vending machine. (With reference to the figure in the attached .gif image)

    There have to be four money input units that correspond to the indicated amounts being inserted into the machine (dollar, quarter, dime, and nickel). Each money input unit consists of a selector and a register or some other means of specifying the amount of money associated therewith.

    There is one product unit which also consists of a selector and a register or some other means of specifying its cost (which should be $1.00). Assume that a product costs less than $1.25 (must use an 8-bit adder). The processing unit itself consists of a full adder that can also act as a subtractor, and three registers (A, B, and C) which are used for temporary storage.

    This is how the system is supposed to work. As long as money is being inserted, register A accumulates the total while the Seven-segment display shows the amount. When the product is selected, its cost is subtracted from the accumulated amount and the result is displayed.

    Do not worry about error checking, e.g., assume that enough money is inserted to pay for the product. In order to get the processing unit to latch the various pieces of data in the A, B, and C registers it will need a control unit and a clock of sorts. Also, it will need a reset button so that the circuit can be properly reinitialized. Finally, I must build the full adder myself using AND, OR, NOT, and/or XOR gates.

    That is basically it.

    If anyone would be able to help me assemble this circuit or even provide advice then super. I don’t know much about registers, etc. and how to arrange everything. Much help.

    (For a bonus, add circuitry to the core processing unit so that it: a) only accepts up to $1.25 worth of input (in any way, shape or form); b) does not dispense a product unless enough money has been deposited (eg use an LED to indicate this), c) will have four products to chose from each with a different price ($1.00, $0.85, $0.65, $0.50); and d) times out and resets itself after one minute if a user selects a product but doesn’t proceed to pay for it. In order to do this lab, you will need to understand overflow and the meaning of the MSB of a 2’s complement number.)
  2. DMahalko

    Active Member

    Oct 5, 2008
    Why isn't this in the Homework Help forum?

    Google search: "In order to do this lab, you will need"
    Last edited: Sep 27, 2012
  3. bertus


    Apr 5, 2008