The brief
The office gate opened with a physical remote: fine for one person, useless for a team. The ask was simple to say and specific to build: open the gate from the phone app people already use, but only when they are actually standing in front of it.
What we built
Rather than reverse-engineer the gate's radio protocol, we converted the manufacturer's own remote: an ESP32 drives the remote's button circuit, so the gate receives exactly the signal it was built to trust.
The ESP32 connects to AWS IoT, and the open control lives inside the existing mobile app. The button only activates within a 50 m geofence around the office, and the electronics sit in a custom 3D-printed enclosure.
Key decisions
Retrofit the remote, not the gate
The OEM remote already spoke the gate's language. Driving it electronically was faster and safer than reverse-engineering a proprietary radio protocol.
AWS IoT in the middle
The device authenticates against AWS IoT rather than trusting phones directly, so access control lives in the cloud, not on the microcontroller.
Geofence as a hard guardrail
Opening a physical gate from anywhere is a liability, not a feature. The control simply does not activate more than 50 m away.
Outcome
- The gate became a feature of an app the team already had.
- Physical access stays local: the button only works on site.
- A tidy retrofit: OEM remote, an ESP32, and a 3D-printed enclosure.
Common questions
- Can an existing gate or garage door be controlled from a mobile app?
- Yes, and usually without touching the gate itself. Here we retrofitted the manufacturer's own remote: an ESP32 drives the remote's button circuit, so the gate receives exactly the signal it was built to trust.
- How do you secure app-controlled physical access?
- Two guardrails. The device authenticates against AWS IoT rather than trusting phones directly, so access control lives in the cloud, not on the microcontroller. And the open button only activates within a 50 m geofence around the office, because opening a physical gate from anywhere is a liability, not a feature.
- Is it better to retrofit existing hardware or reverse-engineer its protocol?
- Retrofit, when the OEM part already speaks the target's language. Driving the original remote electronically was faster and safer than reverse-engineering a proprietary radio protocol.