This pure PHP implementation will read out a magnetic switch and depending on the input, it will control a relay, allowing for a light to be turned on or off.

The idea is that the light will turn on ASAP when the door is opened, and will turn the lights off with a configurable timer when the door has been closed.

It will additionally inform a MQTT broker of the sensors and commands that are being sent.

The materials used for this build are the following:

• Magnetic switch
• Relay
• Raspberry Pi 3b+ (Although any old rPi should be able to handle this program)

The general connections are made using the following diagram:

Disclaimer: Please ignore any errors in above drawing, I'm not an electrician. That being said, above diagram is used to control devices dealing with AC voltage, if you don't even know what "AC" means, DO NOT use this guide and hire somebody that knows about it!

AC voltages CAN kill you!
You don't believe me?

Pin layout is based on this diagram:

This program consists of 2 scripts: one that primarily checks out what the status of the door is and opens up the relay, while the other implements only a timer and will turn the relay down after the door has been closed.

It uses standard symfony components to achieve this. In the case of this program, calling the following script will start the program:

sudo bin/console baseroom:door-sensor

If you want to make it a cronjob, put the following line in your crontab:

*/2 * * * * sudo [ABSOLUTE_PATH_TO_APPLICATION]/bin/console readDoorSensor

This script is run with sudo because it needs access to the GPIO. There might be more elegant ways to solve this issue, but this one is the first one that came up to me and it works.

Check out PHP/GPIO, without that repo, this would be impossible in its current form.