Principle
Each bed has one soil moisture sensor. When moisture falls below the threshold within the allowed time window, the controller opens that bed's solenoid valve for a preset number of minutes.
Components
- Controller (ESP32 or small PLC) + relay module.
- Capacitive soil moisture sensors (more durable than resistive ones).
- 24 VAC or 12 VDC solenoid valves, filter, water meter.
- Power supply with surge protection if cables run long distances.
Control rules
- No watering during harsh midday sun (configurable time window).
- Each watering lasts at most N minutes, followed by a pause of at least M minutes to let the water soak in before measuring again.
- Alert when a sensor keeps reporting dry soil despite watering (clogged nozzle, out of water).
