It-Gets-The-Hose-Again is a Raspberry Pi (compatible with A,B,A+,B+,2, 3, 4, and Zero) controlled Garden sprinkler system that can be controlled via a built in web UI or by HomeKit compatible Apps. This repo includes the source & installation instructions for controller software as well as schematics for the hardware components that need to be added to your Pi in order for the software to control sprinkler hardware.
The controller software is built on Node.js with React.js powering a web UI front end. The software allows a configurable watering schedule and uses OpenWeatherMap to save water by not watering if it is already raining. The controller software is also compatible with Apple HomeKit if you wish to control the sprinkler via HomeKit instead of via the web UI.
The hardware consists of a small circuit to allow the Pi to control a 24vAC/DC solenoid water valve such as this one, and a 3 LED status panel. Valves using different voltages etc should also work with this control circuit, though this has not been tested.
Powered by an AC connection into the enclosure & separate 5v and 24v DC adapters for the Pi and solenoid valve. This configuration requires a Wifi connection to the Pi.
Powered by a PoE+ (power-over-ethernet 802.3at) connection (driven by an injector like this) into the enclosure with a 24v DC PoE+ splitter (like this) that powers the solenoid valve & an additional 24v->5v stepdown transformer (like this) for powering the Pi. This configuration doesn't require Wifi as the PoE connection also provides wired data access.
NOTE: PoE (802.3af) might work for this configuration, but its cutting the power requirements pretty tight - standard PoE can provide 15.4W, which is close to the recommended limit for the Pi 3 of 12.5W or 15W for the Pi 4, without giving much additional ceiling for the valve solenoid.