In November last year — I started building a DIY security alarm system, using a Raspberry Pi as the controller. My plan was to make a self-sustained system, using proper alarm hardware — like PIR sensors and sirens.

Integration with Home Assistant would be an add-on, not a requirement. I wanted the system to be as redundant and fault-tolerant as I could make it.

This is a pretty long story, with some twists and turns — let’s get into it 👇

We recently got balanced ventilation installed, and I have interfaced it with Home Assistant. However — the ventilation unit have three “special modes” that can not be enabled through the Modbus interface; fireplace, kitchen, and override. These can only be set on the touch panel, mobile app, or through inputs terminals on the controller.

So I repurposed an old project and made a three-relay Wi-Fi controlled module, using MQTT to send commands and receive statuses.

Then used Home Assistant to automate it 🙂

Using a few cheap sensors, a wireless keypad, Zigbee2MQTT and Home Assistant; I was able to get a basic security alarm up and running during a free afternoon 🙂

We have a Raspberry Pi driven digital calendar in the kitchen. I’m currently using crontab to turn the HDMI port off at night, and when we’re at work.

But a much more flexible solution is to control it using MQTT and Home Assistant. That way it can easily be automated to turn on when we’re home, if there is movement in the kitchen, or any number of conditions.

It’s really quite easy to do, here’s how 👇

My kids wanted traffic lights for their LEGO city, so first I had to build a traffic lights controller.