This is the first incarnation of an Arduino-based RFID controller for an electric door strike.
This version does not do data logging or refer to an off-controller database for access control information.
Instead, RFID cards are registered directly at the reader.


  The sketch implements a controller for an RFID door lock system.
  It reads RFID cards and sends a signal to unlock a 
  door if the presented card is a valid card stored in EEPROM.
        
  The script currently can interface with HID card readers using Wiegand26
  protocol or with Innovations' ID-12 or ID-20 readers configured for 
  serial ASCII protocol.  The latter reads 125 KHz RFID cards / keyfobs.
   
  Additional features:
  1) System begins in 'factory default' mode. This is a 'virgin'
     state with no stored cards. When in this mode, lights flash in 
     a frenetic way. The first RFID card read after installation
     will become the 'master card' and factory default mode is exited.
     This little feature means you can burn tons of these chips and
     you don't need to hard-code any RFIDs. Suitable for shipping!
       
  2) Master card (first card read after installation) also opens
     the door, so you can just use that card for every day access
     instead of having to stash it somewhere.
        
  3) You can enter programming mode at any time with the Master card.
     To do this, you swipe the master card twice within a few seconds.
     First time opens the door, and second time (if door is still 
     unlocked) puts you in programming mode. You get sequential flashing 
     lights to indicate you are in programming mode.
    
  4) While in programming mode you can add any number of additional
     cards to the EEPROM. You can also remove any number of 
     cards from EEPROM while in this mode. You get a blinking green for
     adds and a blinking red for deletes. Previously unauthorized cards 
     will be added and authorized cards will be deleted. You exit 
     programming mode by swiping the master card again or after a period
     of inactivity.
			    
  5) Master card and other cards get a green/red light indicating
     pass/fail when trying to open the door.

  OPTIONAL FEATURES
  1) Master Swap option allows you to change the Master without
     resetting to factory default mode and erasing the additional
     cards. This is useful if you lose the Master card. Hold optional
     controller reset button for around 5 seconds.
  2) Device can be returned to factory default mode by pressing the 
     optional reset button for 15 seconds.
  3) Stealth option (not implemented) allows you to add your own RFID 
     card to the controller without having the Master card. Warning: Evil
			      
  DEVELOPMENT FEATURES
  1) Define a debug flag to get serial debug output.

  FUTURE POSSIBILITIES
  Data logging via wireless or HDSD card or enet/USB connector.
  Command line over serial to query and edit RFID database.
  IP web service interface for querying remote RFID db.
								      
  HARDWARE CONFIGURATIONS
  * Homegrown DIY using ID-12 or ID-20 RFID Reader
    I suggest two PCBs, one for the RFID reader and indicator lights 
    outside the door and a second for the controller inside. 
    Connect reader serial and light control lines to controller 
    located in a secure location (inside the access-controlled area). 
    Power for the door lock should be routed securely from the
    controller board to the door lock to prevent jumping. If you
    are providing a factory reset switch, some means of access to 
    the switch needs to be provided.
  * ProxPoint Plus Proximity Reader with Wiegand Output Model 6005
    For this you just need the interior controller connected to
    the reader outside the door, and power from the controller to
    the door lock.


  I've included Eagle files for the controller board and 
  Eagle files for the reader board for the ID-12/ID-20 chip
  configured for ASCII protocol.  You won't need the reader
  board if you're using a purchased HID Wiegand reader.