Smart Gate Opener: Control Your Rolling Code Gate With Home Assistant

For this project, I encountered a particularity of modern automatic opening systems: 433 MHz remote controls with rolling code technology. These devices offer a high level of security, which is certainly an advantage in preventing unauthorized access. However, this very security introduces a practical limitation when it comes to obtaining a copy of the remote.

Unlike fixed-code remote controls, which can often be duplicated by simply "cloning" the signal from a working remote, rolling code systems operate significantly differently. The core of their security lies in the fact that with each button press, the remote transmits a unique and different code. This code is not static but follows a complex algorithm synchronized with the receiver. Consequently, intercepting and replicating a single transmitted code is useless, as it will not be valid for subsequent openings.

Duplicating a rolling code remote control is therefore not a trivial operation that can be performed in an external laboratory. Programming a new remote requires direct interaction with the receiving unit (the control unit of the gate, garage, etc.). This procedure involves the use of a "secret key," which can be a specific sequence of buttons to be pressed on the receiver and/or the new remote, or a unique programming code stored in the control unit.

And this is where my problem arose: I found myself in a situation where I needed a duplicate of the remote control quickly, but the standard procedure required access to the receiver, which was not immediately possible. This limitation prompted me to use ingenuity to explore and implement an alternative solution, which I will illustrate in the subsequent steps of this project!

Spoiler alert: it's not cheap!

1. Raspberry Pi 4 4GB
2. 16GB SD Card with Home Assistant installation
3. Wi-Fi Relay 1 NO Dry contact (if is possible!!)
4. Power Supply 230Vac to 3.3Vdc
5. Already programmed Remote controller for the gate
6. Waterproof box

First, we need to identify the contact of the opening button on the remote control. Near these contacts, we need to solder two wires (red and blue), which will allow us to open our gate via a relay.

The remote control obviously needs to be powered. By default, most remote controls use a CR2032 battery which has a very low capacity in terms of mAh. Furthermore, extreme winter temperatures further reduce its capacity. Therefore, it is necessary to install an additional power supply (3V 700mA) to always have maximum signal performance in all conditions, which is crucial in my case because the remote control will be located far from the gate receiver. To do this, we need to identify the +3V and GND of the original battery (white/green and green wires).

I used an old eWelink relay, but it had a problem: it wasn't a dry contact. Therefore, I had to install an additional supporting relay. I used a finder relay 40.52.8.230.

Having difficulty reaching the gate receiver from the transmitter's location, I created a script that makes 50 attempts to open it. Ugly but effective!

This is the final result, let me know what you think!