7 digit code system fails (logisim circuit project)

Discussion in 'The Projects Forum' started by zoliking, Jun 8, 2011.

  1. zoliking

    Thread Starter New Member

    Jun 8, 2011

    I'm working on a very small logic circuit project in logisim, but I'm a just dumb programmer so I don't have much experience with circuitry, ergo I failed.

    The goal of the project is to create a system that has 7 buttons as inputs and they need to be pressed in a certain order for the output to be true.

    The way I approached it (as seen in the diagram) is that I keep track of where we are in the code sequence in a register. The value stored in the register serves as a selector for a multiplexer to which the inputs are the constants that store the actual code.
    When a button is pressed the value coming out of the multiplexer is compared to the value of the button and if they are the same the value stored in the register is incremented. If they are different, then the register is reset to 0.

    My problem is that once the register updates the next value is compared, to the button pressed currently, which resets the register. I was trying to find a workaround but so far I couldn't come up with a working one, and so I need help finding one. (I also welcome general observations if there is something else wrong with the circuit.)


    Circuit diagram: