fhu_auto

FHU door Raspberry Pi controller.

This repository has been fully migrated away from ROS. It is now a small, self-contained Python Flask application that drives the gate relays through the Raspberry Pi GPIO pins, and exposes a web UI plus a simple HTTP/JSON API.

Requirements

• Python 3.5+
• A Raspberry Pi with the two relay channels wired to the GPIO pins configured in app.py (default: GPIO19 for up, GPIO26 for down).

Installation

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

RPi.GPIO is only required (and only installable) on a Raspberry Pi. When running the app on a regular PC (e.g. for development or UI testing) a mock GPIO backend is used automatically and GPIO calls are just printed to the console.

Running

python app.py

By default the server listens on 0.0.0.0:5000. The following environment variables can be used to configure it:

Variable	Default	Description
PORT	5000	TCP port the Flask server listens on.
UP_GPIO	19	BCM GPIO pin driving the "up" relay.
DOWN_GPIO	26	BCM GPIO pin driving the "down" relay.
DOOR_TIME	17	Seconds the relay stays energised for a move.
GATE_LAT	53.268684	Latitude of the gate, used for geofencing.
GATE_LON	-0.524170	Longitude of the gate, used for geofencing.
GEOFENCE_RADIUS_M	50	Radius (metres) within which Up/Down can be operated.
LOG_FILE	gate_control.log (next to app.py)	Path to the command log file.

Web UI

Open http://<pi-address>:5000/ in a browser (desktop or mobile). The page offers three buttons:

• Up – raises the gate.
• Down – lowers the gate.
• Stop – immediately stops any gate movement.

Pressing Up or Down opens a confirmation dialog with a safety warning. The dialog must be confirmed by pressing and holding the confirm button for two seconds (works with mouse and touch) before the command is sent, to avoid accidental activation. Stop is a safety action: it is executed immediately without confirmation, is never geofenced, and is also available as a button inside the confirmation dialog itself, so a move can always be interrupted.

On load, the page requests the browser's location and compares it against the configured gate position and radius. Up and Down stay disabled, and a status line explains why, until the client is confirmed to be within range; Stop is never affected by this check.

The page also shows the likely current state of the gate (open, closed or unknown, since the actual door position can't be read back from hardware) and a "Recent commands" list with the last 10 commands issued.

The UI is responsive and usable on both desktop and mobile screens.

Note: browsers only expose geolocation on secure origins (HTTPS or localhost), so serving the app over plain HTTP on the LAN may prevent Up/Down from ever becoming available in the field unless TLS is set up.

HTTP/JSON API

Method	Path	Description
GET	/	Serves the HTML control page.
GET	/api/status	Returns the current status as JSON (see below).
POST	/api/up	Starts raising the gate. Requires a JSON body {"lat": float, "lon": float} with the client's location. Returns 403 if outside the geofence, 409 if a move is already in progress.
POST	/api/down	Starts lowering the gate. Same location requirement and error codes as /api/up.
POST	/api/stop	Immediately stops any movement and releases both relays. Never geofenced, always returns 200.

/api/status (and the other endpoints) return a JSON body describing the resulting status, e.g.:

{
  "busy": true,
  "direction": "up",
  "message": "Raising the gate...",
  "last_command": "up",
  "last_command_time": "2026-08-21T10:15:00+00:00",
  "likely_state": "unknown",
  "history": [
    {"command": "up", "time": "2026-08-21T10:15:00+00:00"}
  ],
  "geofence": {"lat": 53.268684, "lon": -0.524170, "radius_m": 50}
}

Every command (up, down, stop) is also appended, with its timestamp, to the local log file configured by LOG_FILE.

Running as a service

An example supervisord program definition is provided in config/sv-door-control.conf to run the Flask app as a persistent service on boot.