Turn Your Normal Door Into a Smart Door with Alexa + Home Assistant
Ever worried that your kids might open the door and walk outside without you noticing?
That’s exactly the problem I wanted to solve.
In this project, I converted my normal door into a smart door using a Zigbee door sensor, Home Assistant, and Alexa announcements.
Now whenever the door opens:
- Alexa instantly announces it
- My phone gets notified
- I can track door status in real time
And the best part?
It’s cheap, simple, and beginner-friendly.
What You Need
- Zigbee Door Sensor
- Home Assistant
- Alexa
- Zigbee2MQTT
That’s it.
How the Door Sensor Works
A typical door sensor comes with two parts:
- Main Sensor
- Magnet
When the magnet stays close to the sensor:
- Door = Closed
When the magnet moves away:
- Door = Open
Very simple concept.
The sensor continuously sends the status to Home Assistant through Zigbee2MQTT.
Home Assistant Automation
Once the sensor is paired with Zigbee2MQTT, it automatically appears inside Home Assistant.
From there, we can create automations like:
- Alexa announcements
- Phone notifications
- Smart lock status
- Security alerts
- Night-time reminders
Example:
If the door opens, Alexa can say:
>
Going One Step Further — Lock Detection
Detecting only “door open” wasn’t enough for me.
I also wanted to know:
- Is the door LOCKED?
- Or just CLOSED?
Initially, I tried mounting the magnet directly on the knob.
It worked inconsistently.
So I designed a custom 3D-printed solution to hold the magnet properly inside the lock mechanism.
Now Home Assistant can detect:
- Locked
- Unlocked
- Open
- Closed
Much cleaner and more reliable.
3D Printed Design
I quickly designed a custom holder and printed it using my 3D printer.
The design is already uploaded to MakerWorld.
You can download and print it yourself.
Final Result
Now my setup can:
- Detect door open/close
- Detect lock/unlock
- Send phone notifications
- Make Alexa announcements
- Improve child safety
- Integrate with smart home automations