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As we moved to the new Computer Science Department building, we have a completely new door to install the door lock. Currently, some progress has been made to reinvent the door lock mechanism but there is still some work to be done so it can work again.


The mechanical part consists of 1 Stepper Motor and 2 3D-printed gears, with the following specs:

Gear A

Radius mm / tooth Thickness
24 mm 8.5 10 mm

The first gear is attached to the Stepper Motor.

Gear B

Door lock v2 big gear.png
Radius mm / tooth Thickness
72 mm 8.5 10 mm

The second, largest gear has a total of three (3) circular holes and features a τolabάκι hackerspace sign on it. This one is attached to the door knob.


The Stepper Motor is driven by an Arduino board. The board runs custom software that is available for free for use and modification. The Arduino receives a signal from a computer or another sensor and then proceeds to open the door or lock it again. It has a special reset mechanism to run upon initialisation just in case of a power failure. The code also includes support for an error LED which blinks in a specific pattern if something goes wrong.

Trigger Methods

A number of triggering methods have been found, some are easier than others. We will try to cover as many methods as possible. All methods have to be relatively secure and restrict access to members of ToLABάκι only.


The idea is that the members can call a phone number using their mobile phones, and after the computer checks if the Caller ID is whitelisted, proceed to open the door. Since the procedure is done in a computer, we can keep access logs of persons and timestamps. This method requires ToLABάκι to pay a monthly fee for the VoIP service and also requires a computer alongside the existing setup.


This method is theoretically simple: Members can pair with a specific Bluetooth device inside ToLABάκι and after a check (of MAC Address or Passcode) the door opens. Currently there is no planning on how this will work, for example, if we will simply send a file or have a dedicated application.


The only way to access the Computer Science Department Building is currently with an RFID card. We could incorporate cards owned by members of ToLABάκι to the door lock mechanism or find a way to issue access cards ourselves. This method has the advantage of access logging as well, and also provides the ability to issue limited timeframe cards to some people who are not members. It requires special equipment, like an RFID tag reader / writer which may be costly.

RF Controller

Another method of access could be a simple garage door remote, on a specific tone and frequency. This method requires members to have a remote with them to open the door. We can get some cheap remotes if necessary from the Internet, but we also need a receiver inside ToLABάκι.


A way that utilises the WiFi provided by ToLABάκι and HWMN could be to have a website within the area where after supplying a password you could control the door mechanism, for example open it or close it. It can either be a local machine within ToLABάκι so you can only trigger it locally or available via HWMN.

Mobile Application

An application for the iPhone and iPad can be designed that will give the members who own such a device the ability to control the door from something they always carry with them. This can work out really easily if the Website method is implemented correctly.

Post Authentication

After someone successfully authenticates using one of the methods above, we should try to incorporate special functions to the Door Lock. They do not have any interaction with the procedure of getting in, but may add some functionality or just be cool. Currently the following have been proposed:

Notification System

When the door opens, we send a Push Notification to all our subscribers on their web browser that ToLABάκι is open and they can pass by anytime. For this, we will use the Safari and Chrome built-in notification system, so the subscribers do not have to be on the homepage to receive this notification.


We could use a speaker to make an one-tone noise when the door opens, just as we see in the movies. :)