Need help in Keypad Door Lock project ..

Discussion in 'The Projects Forum' started by gautamamrit24, Dec 30, 2013.

  1. gautamamrit24

    Thread Starter New Member

    Dec 30, 2013
    4
    0
    Hi Everyone ...
    I am first year engineering student. I am given the project:

    Key pad door lock has five buttons on the outside and one button on the inside. The outside buttonsare numbered 1 – 5. When the code 3-1-5 is pressed the lock opens after the last correct digit (gives an opening pulse to the lock mechanism). When the inside button is pressed the lock opens immediately.
    Design key pad door lock according to the specification above . Make sure that no other combination opens the lock and pressing more than one key simultaneously does not open the lock.

    Since i am very new to this sujbect, I have done the simple combinational Circuit design using Logisim of K-map.
    I have problem in making the circuit sequential. I have no idea how to store 3-1-5 input consecutively and only this sequence of number opens the locked door. I am confused where and how do i need to use flip-flops and different states.

    I will be grateful if anyone help me .................. I have attached my simple combinational circuit Diagram ...
     
  2. mitko89

    Member

    Sep 20, 2012
    123
    19
    Can't you use a uController?
     
  3. Nykolas

    Member

    Aug 27, 2013
    87
    31
    This should work:
     
    gautamamrit24 likes this.
  4. gautamamrit24

    Thread Starter New Member

    Dec 30, 2013
    4
    0
    Hello Mitko89,

    Thanks alot for giving interest in my question. I have not heard about ucontroller.

    I need to just design the digital circuits by using the logic gates only like using latches, state registors. I have no idea how to use latches, flip flops different states ?
     
  5. gautamamrit24

    Thread Starter New Member

    Dec 30, 2013
    4
    0
    Hi Nykolas,

    Thanks for your great effort. Can you help me little further ? I am designing the logic level based circuit and I have used Logisim to draw those gates in computer. But I cannot find Latch in the memory section of this program so that i can simulate the design but there are d,t, j-k flip flops etc. Can you tell me how can i draw these Latches and reset in Logisim ? Why there is no latch in 5 input ?

    I am just a beginner in this topic so can you please jot down the truth table or any other logic you have applied here ? Are there any states involved. It would be a great help for me :)
     
  6. Nykolas

    Member

    Aug 27, 2013
    87
    31
    To the OP:
    This is a concept only. As a first year student you should be able to work out the rest on your own. The purpose of a forum is not he spoon-feeding of detail! E
     
  7. gautamamrit24

    Thread Starter New Member

    Dec 30, 2013
    4
    0
    Ok Nykolas .. I will try to do own my own. Thanks for the drawing. :)
     
  8. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    One of the first things you need to do is determine your state transition table(or diagram), indicating what happens when you are in state x, and get the correct and incorrect inputs.

    Perhaps the ebook section on finite state machines will help you...
     
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