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Carhole Minder

Carhole Minder is a ruby application intended for use on a Raspberry Pi (B, B+, 2B, 3, etc). It is an internet-enabled garage-door opener and closer with a built in timer and alerting.

It has been tested with a Liftmaster garage door opener. The generations of these openers are identified by the color of the "Learn" button on the back. Mine is a purple button opener. It may work with other garage door openers (assuming you need only short two wires to send a signal to open the door); but, you're mileage may vary. I assume NO responsibility for the use of this project by anyone else and simply offer it as open source in the case that someone else can benefit.

Project Hardware Requirements

To create this project, you'll need the following components:

  • A Raspberry Pi (I recycled an old B I had lying around; but, any will do)
  • 1 LED for the power indicator
  • 3 LEDs (preferably a different color from the power LED) for timer status indication
  • 2 buttons, preferably with built in LEDs (I used these Adafruit Mini Arcade Buttons)
  • A magnet switch with a "normally open" option, as typically used by alarms (I used this)
  • A 5V relay module (I used this as it was in stock at my local electronics store; but, you don't need two relays)

Building the Hardware

Please check my blog here for a write up on how I built the hardware and what components I used.

Project Software Requirements

  • Ruby >= 2.3
  • Ruby Development Headers
  • Bundler

Installing Requirements

Note that all of the instructions on this page assume that you're running a recent version of Raspbian or another Debian variant on a Raspberry Pi.

  1. Install ruby and ruby development headers

     sudo apt-get install ruby ruby-dev
  2. Install bundler gem globally

     sudo gem install bundler

Building and Testing the Software

  1. Clone the repository into a local folder

     git clone git@<server>:<path>/carhole_minder.git
     cd carhole_minder
  2. Install the Bundled Gems (local to the project or another path, if you prefer)

     bundle install --path=vendor/bundle
  3. Copy the default configuration (constants.rb.default) to constants.rb

     cp constants.rb.default constants.rb
  4. Test the software by running the daemon_start.rb file

     bundle exec ruby daemon_start.rb

You should now see "Initializing pin states" and "Enabling timer" on the console. Additionally, the timer and door button LEDs should fully illuminate.

Starting on System Startup

You probably don't want to have to login and start your garage managing service every reboot, so edit the carhole.service file and change WorkingDirectory to the path where you cloned the project. Additionally, if you cloned the project using any other user than pi, modify the User and Group entries accordingly (any user must be in the gpio group for the software to work properly).

Once you've made those changes, copy the service file to /etc/systemd/system (using sudo) and reload the the systemd daemon.

sudo cp carhole.service /etc/systemd/system/
sudo systemctl daemon-reload

You should now be able to see your service status using systemd.

sudo systemd status carhole.service

Start the service using systemd and enable it to start on boot.

sudo systemd start carhole.service
sudo systemd enable carhole.service


Copyright 2018 Aaron M. Bond

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.


Garage door controller software for use with a Raspberry Pi.




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