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Combination Lock

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					Combination Lock
      Engineers:
    Aaron Pickard
     Steve Baker
Abstract
• It is expected that a
  combination lock should
  provide a secure way of
  keeping intruders out.
• Security features:
   – Anti-tampering
   – Low probability of
      guessing correct
   – Ability to change
      password if needed
Background Information
• Create a Verilog HDL 4 digit combination
  lock with 0-9 and clear keys.
• A number of failed attempts will freeze the
  system for a length of time.
• A correct code entry will unlock the system
  and re-lock upon the door being closed.
• A correct code also gives the user the
  opportunity to set the password to a new
  value.
Requirements
• Synchronize user inputs
• Keep track of how many keys have been
  pressed
• Keep track of the number of failed attempts
• Remain in lock-out mode for a certain length
  of time
• Decide whether the user has permission to
  change the password
The Layout
The Keypad
             • Synchronize user
               inputs
             • Output corresponding
               code and valid signal
The Keypad cont.
The State Machine
                • Next state logic and
                  Register transfers
                • Compares user’s codes
                  with password
                • Determines when to
                  lock-out, unlock, or
                  change password
                • If input is the Clear
                  Key, start at T1 again
The State Machine cont.
Testing the Set feature
The State Machine cont.
Testing the Clear key
The State Machine cont.
Testing 3 fails
How to Improve It
• Add a 4 digit 7-segment display module to
  show how many codes have been entered.
• It would also display the actual keys pressed
  for verification when changing the password.
Questions?

				
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posted:2/18/2012
language:English
pages:13