ActionPi

Turn a Raspberry Pi + camera into a standalone, web-controlled action / underwater camera. Everything is controlled from a phone browser over the Pi's local network — no screen, no buttons, no buzzer, no internet required.

ActionPi is built for the one thing that makes underwater use hard: the connection drops all the time, and that's fine. Recordings run entirely on the Pi, independent of your phone. If you walk out of Wi-Fi range mid-timelapse, the browser keeps estimating the time remaining and shows a disconnected badge; when you reconnect it re-syncs to the real camera state. Refreshing or reopening the page never starts a second recording.

Features

• Photo, Video and Timelapse capture, started from the web UI.
• Non-blocking: starting a capture returns instantly; the camera runs in the background. Only one capture runs at a time, and starting is idempotent.
• Connection-loss friendly: live countdown of remaining recording time that keeps running while offline and re-syncs on reconnect.
• Gallery: browse photos, videos and timelapse folders. View full-size, play videos, step through timelapse frames, download or delete — individually or multi-select.
• Fast downloads: single files stream directly; folders and multi-selections stream as an uncompressed zip on the fly — no re-zipping, no temp files, easy on a Pi Zero.
• Self-contained: no CDNs. All CSS/JS is served from the Pi so it works with zero internet access.
• System status: battery level (UPS-Lite HAT), CPU temperature and disk space; shutdown / reboot buttons.
• Built-in Debug screen: a Debug button opens live diagnostics (camera, battery, Wi-Fi, system) and a streaming log console right in the browser, so you can see exactly what's happening — and why, say, the battery isn't reporting — without SSH.
• Battery monitor: reads percentage + voltage from a UPS-Lite fuel gauge over I2C and estimates charging / discharging.
• Wi-Fi self-healing (optional): disables Wi-Fi power-save and auto-reconnects if the Pi's Wi-Fi client link drops.

Hardware

• A Raspberry Pi with Wi-Fi (a Pi Zero W works).
• A camera module supported by libcamera (libcamera-still / libcamera-vid).
• (Optional) a UPS-Lite V1.3 battery HAT for the battery indicator.

No GPIO wiring, sensors or buzzer needed.

Install

Clone onto the Pi and install the dependencies:

git clone https://github.com/jakobkreft/ActionPi.git
cd ActionPi

# System camera + video tools (usually already present on Raspberry Pi OS)
sudo apt-get update
sudo apt-get install -y libcamera-apps ffmpeg python3-flask python3-pil

# Optional: battery monitoring on the UPS-Lite HAT
sudo apt-get install -y python3-smbus

# Or, if you prefer pip:
# pip3 install -r requirements.txt

Media is stored under ~/camera by default (photos/, videos/, timelapses/, thumbnails/). Override with the ACTIONPI_DIR environment variable.

Battery monitor (UPS-Lite)

The battery indicator reads a UPS-Lite fuel gauge over I2C, so enable I2C once:

sudo raspi-config    # Interface Options -> I2C -> Enable

If no UPS-Lite / I2C is present the app simply hides the battery indicator.

Wi-Fi auto-reconnect (optional)

Set ACTIONPI_WIFI_WATCHDOG=1 (already set in actionpi.service) to have ActionPi disable Wi-Fi power-save and automatically reconnect the Pi's Wi-Fi client link if it drops. It uses passwordless sudo for a few network commands (default on Raspberry Pi OS).

Only use this when the Pi connects to an existing Wi-Fi network. Do not enable it if the Pi hosts its own hotspot — it would bounce the connection your phone is on.

Run

python3 server.py

Then open http://<pi-ip>:8000 from your phone on the same network (or the Pi's Wi-Fi hotspot).

If libcamera-still isn't installed (e.g. you're testing on a laptop), ActionPi automatically runs in mock mode and generates placeholder media so you can try the whole interface without a camera.

Run at boot (systemd)

An actionpi.service unit is included. Edit the User, WorkingDirectory and paths if your username isn't pi, then:

sudo cp actionpi.service /etc/systemd/system/actionpi.service
sudo systemctl daemon-reload
sudo systemctl enable --now actionpi.service

Check logs with journalctl -u actionpi -f.

The Shutdown / Reboot buttons call sudo shutdown / sudo reboot. On Raspberry Pi OS the default user already has passwordless sudo; otherwise add a sudoers rule for those two commands.

Debugging

Tap Debug at the bottom of the page (or open it directly) to see:

• Diagnostics cards for camera, battery, Wi-Fi and system, each with a status badge. The Battery card shows precisely why it may not report — e.g. smbus_module: — (install python3-smbus), i2c_device_present: no (enable I2C), or reads_failed with the exact error (UPS-Lite not detected; check i2cdetect -y 1).
• A live log console with level filtering (Debug/Info/Warnings/Errors). Unhandled server errors appear here in red, with their full traceback.

The same data is available as JSON at /api/debug and /api/logs, and the full log downloads from /api/logs/download. Everything is also written to the console (journalctl -u actionpi -f) and to a rotating actionpi.log in the media directory.

How it works

Part	File
Camera controller — background capture, state persistence, crash recovery	camera.py
Web server — REST API, media listing, streaming downloads, system status	server.py
Central logging — ring buffer + rotating file, shared by all modules	logsetup.py
Battery monitor — UPS-Lite fuel gauge over I2C, with diagnostics	battery.py
Wi-Fi reconnect watchdog	wifi.py
Single-page web UI (offline-resilient) with Debug screen	templates/index.html, static/

The browser polls GET /api/status, which returns the camera state together with the server clock and the recording's ends_at timestamp. The UI uses these to count down locally, so the estimate stays correct even with no connection.