We’ve all been there. You’re ten minutes into your morning commute, sipping your lukewarm coffee, and suddenly a cold sweat washes over you: Did I close the garage door? You try to visualize pressing the button, but you can’t remember. Is your prized collection of half-finished projects and rusty drill bits currently exposed to the neighborhood?
Instead of turning around and being late for work, let’s fix this permanently. We’re going to build an ESP32 Smart Garage Door Controller. It uses a relay to act like a virtual finger pressing your wall button, and a magnetic reed switch to definitively tell you if the door is actually closed. No more guessing, no more paranoia, and absolutely no more turning the car around.
What You Need
- ESP32 Development Board (Buy on Amazon)
- 5V Relay Module (1 Channel) (Buy on Amazon)
- Magnetic Reed Switch Door Sensor (Buy on Amazon)
- Jumper Wires & Long Spool of Wire
- A Garage Door Opener (Obviously)
Step 1: The Virtual Finger (The Relay)
Most garage door openers have two terminals on the back where the wall-mounted button connects. If you short these two terminals together with a piece of wire, the door opens or closes. That’s exactly what our relay will do.
- Connect the VCC of the relay to the 5V (VIN) pin on the ESP32.
- Connect the GND of the relay to GND.
- Connect the IN pin of the relay to a digital output pin (like GPIO26) on the ESP32.
- Run two wires from the Common (COM) and Normally Open (NO) terminals on the relay to the two wall-button terminals on your garage door motor.
When your code pulls GPIO26 HIGH for half a second, the relay clicks, the terminals short, and the door moves. Magic.
Step 2: The Truth Teller (The Reed Switch)
Knowing you can open the door is great, but knowing if it’s actually closed is the real goal here. That’s where the magnetic reed switch comes in.
Mount one half of the switch on the garage frame and the magnet half on the door itself.
- Wire one side of the switch to GND.
- Wire the other side of the switch to a digital input pin (like GPIO27) on the ESP32.
In your code, set GPIO27 to INPUT_PULLUP. When the door is closed, the magnet pulls the switch shut, connecting GPIO27 to GND (reading LOW). When the door opens, the switch breaks, and the internal pull-up resistor pulls GPIO27 HIGH. Now you know for sure if your tools are safe!
Tie this into Home Assistant or a custom web dashboard, and you can officially stop worrying during your morning commute.