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Gatekeeper is the first node of our Hackspace Instrumentation project to go live and is responsible for access control to the space through the front "Airlock" door. An updated version is also used for the back entrance upstairs and several access doors downstairs.



Source Code

The firmware that runs on the arduino can be found here
The code for the database and the process that run on Holly can be found here, the relevant part is GateKeeper.cpp The PCB and housing designs can be found here


Gatekeeper Shield.png

Station Controller Interface.png

Logic Flow

Gatekeeper Logic Flow.jpg

Quick Breakdown

  • Arduino with Wiznet shield
  • RFID reader
  • Doorbell button (interrupt pin)
  • magnetic release (MOSFET switch 12v)
  • Magnetic contact
  • Doorbell sounder (Relay) - activated either by attached doorbell button, or doorbell on outer door (connected to main LED Matrix display)
  • Magnetic release status led's red/blue (TODO)
  • Matrix keypad and HD44780 LCD controlled via I2C AtTiny2313
  • MQTT
  • MQTT scripts on holly push door opened & last man switch events to irc twitter and log
  • Card numbers in 'Instrumentation' MySQL database on Holly
  • Database managed by HMS


6 Core alarm cable run to airlock door

  • magnetic contact on black and white core
  • door magnetic release green and yellow cores
  • last man switch on blue and red cores



Some time the V1 hardware on the Airlock door needs resting by hand
The main board is located to the left of the Cash Acceptors in the Members storage area
Gatekeeper V1 Rear Context.jpg

Cycle the power first by toggling the switch indicated by the purple arrow, then reset the Arduino (Red arrow)
Gatekeeper V1 Reset Switch.jpg


Open the grey box and hit the reset switch