FlowerWeb

Written with support from ChatGPT and Claude

A small web-controlled watering system for a Raspberry Pi. Open the web page from anywhere (for example over Tailscale), watch your plants on a live camera, water them with one click, or let a timer do it every 24, 48 or 72 hours.

The server is written in Free Pascal / Lazarus and runs as a systemd service. The camera stream is served by MediaMTX.

Features

• Manual watering: opens the valve for a set time (1–60 s by default)
• Automatic watering: every 24, 48 or 72 hours. The schedule survives restarts, and a watering missed while the Pi was off runs when it comes back.
• Live camera: a WebRTC stream from a USB webcam or the Raspberry Pi camera
• Status: shows the Pi's IP address, CPU temperature, next watering time and a countdown while watering
• Remote reboot from the web page
• Safe valve handling: the valve is closed at startup, at shutdown, when the service crashes and before a reboot, and the server enforces a maximum opening time

Hardware

Part	Notes
Raspberry Pi	Any model with GPIO. Uses pinctrl (Pi 5 / Bookworm) or raspi-gpio (older models)
Relay module	Signal on GPIO 18 by default. Active-high and active-low boards are both supported (ActiveLow in the ini)
Water valve or pump	Switched by the relay. Use a separate power supply that suits the valve
Camera	USB webcam (/dev/video0) or Raspberry Pi camera module

A ready-made Raspberry Pi HAT for all of this is in hardware/kicad. It has a 5 V 6 A input jack, a 24 V step-up module, a TIP121 valve driver on GPIO 18, a 24 V valve jack and a status-LED header.

⚠️ The relay switches the valve's supply, not mains power. If your valve or pump runs on mains voltage, use a suitably rated relay and have the wiring checked by someone qualified.

The KiCAD hat board meant as a suggestion. No frills here, only GPIO18 is connected.

Project layout

flowerweb/
├── src/        Pascal source (Lazarus project flowerweb.lpi)
│   ├── flowerweb.lpr   program start, HTTP routes
│   ├── uconfig.pas     reads/writes config/flowerweb.ini
│   ├── uRelay.pas      valve control and watering timer
│   ├── uapi.pas        REST API
│   ├── uwebfiles.pas   serves the web page
│   ├── usysinfo.pas    CPU temperature and IP address
│   └── ulog.pas        logging
├── web/        index.html, app.js, style.css
├── config/     flowerweb.ini, mediamtx.yml (USB camera), mediamtx.yml_rpicam (Pi camera)
├── systemd/    flowerweb.service, mediamtx.service
├── scripts/    deploy.sh (build and install on the Pi), reset.sh (Wi-Fi watchdog)
├── hardware/   kicad/: FlowerWeb HAT schematic, board layout and BOM (see its README)
└── docs/       notes and command reference

On the Pi everything lives in /home/flowerweb, and the compiled program goes in /home/flowerweb/bin.

Installation on the Raspberry Pi

1. Install Lazarus (for lazbuild) and create the folders:

   sudo apt install lazarus
   sudo mkdir -p /home/flowerweb/bin
   sudo chown -R pi:pi /home/flowerweb

2. Install MediaMTX for the camera. Download the ARM build from the MediaMTX releases and put mediamtx in /home/flowerweb/bin. Copy the config that matches your camera:

   cp config/mediamtx.yml        /home/flowerweb/bin/mediamtx.yml   # USB webcam (needs ffmpeg)
   # or
   cp config/mediamtx.yml_rpicam /home/flowerweb/bin/mediamtx.yml   # Pi camera module

3. Allow the service commands without a password (sudo visudo -f /etc/sudoers.d/flowerweb):

   pi ALL=(root) NOPASSWD: /usr/sbin/reboot, /usr/bin/systemctl
   

4. Install the services:

   sudo cp /home/flowerweb/systemd/*.service /etc/systemd/system/
   sudo systemctl daemon-reload
   sudo systemctl enable --now mediamtx flowerweb

Building and deploying

Development happens on a PC. scripts/deploy.sh copies the source to the Pi over SSH, compiles it there with lazbuild, installs it and restarts the service:

./scripts/deploy.sh

Set PI_HOST in the script to your Pi's address. Password-free SSH login is described in docs/.

Testing without touching the live system

./scripts/deploy-test.sh          # copy, compile and start a test copy on port 8081
./scripts/deploy-test.sh log      # follow its log
./scripts/deploy-test.sh stop     # stop it

The test copy runs from ~/flowerweb-test on the Pi in simulation mode. It only logs what it would do and never switches the relay or reboots the Pi. The live service, its folder and port 8080 are left alone. An orange banner on the page shows you're on the test copy. Simulation mode can also be switched on with Simulate=1 in the ini or --simulate on the command line.

The Pi's config/flowerweb.ini is copied only the first time. After that, deploy leaves it alone so the settings you made from the web page are kept.

Configuration

config/flowerweb.ini:

Section	Key	Default	Meaning
Server	Name	FlowerWeb	Title shown on the web page
Server	Port	8080	HTTP port
Relay	Pin	18	GPIO pin for the relay
Relay	ActiveLow	0	1 if the relay switches on when the pin is LOW
Relay	PulseTimeMS	5000	Valve opening time (set from the web page)
Relay	MaxPulseTimeMS	60000	Longest allowed opening time
Relay	TimerInterval	0	Hours between automatic waterings, 0 = off (set from the web page)
Relay	NextWatering		Written by FlowerWeb. Next scheduled watering
Camera	Name / Port	cam / 8889	MediaMTX path and WebRTC port
Logging	Level	INFO	INFO or ERROR

Logs are written to /home/flowerweb/logs/flowerweb.log, which rolls over at 1 MB.

Remote access

FlowerWeb has no login, so anyone who can reach port 8080 can water the plants and reboot the Pi. Keep it on your local network and reach it from outside through a VPN such as Tailscale. Don't forward the port to the internet.

Then open http://<pi-address>:8080 in a browser.

API

Method	Path	Body	Description
GET	/api/status		Status JSON (IP, temperature, timer, watering state, …)
POST	/api/trigger	{"pulseTimeMS": 5000} (optional)	Start watering. Returns 409 if already watering
POST	/api/timer	{"timerInterval": 24}	Set the automatic interval in hours (0 = off)
POST	/api/reboot		Close the valve and reboot the Pi

Close the valve by hand at any time:

/home/flowerweb/bin/flowerweb --relay-off

License

FlowerWeb is released under the PolyForm Noncommercial License 1.0.0. You're free to use, study, change and share it for any non-commercial purpose: personal projects, hobby use, education, research, and charitable or public organisations. Commercial use is not permitted without the author's permission.

Copyright (c) 2026 DL1BWA