IoT

Building a Smart Irrigation System with ESP32: System Architecture

An ESP32 irrigation controller combines sensing, decision logic, a protected valve driver and optional Home Assistant integration into one testable system.

Publisher / public contact: Vitaliy Panasiuk

Published 2026-09-29Updated 2026-10-17
  • esp32
  • smart-irrigation
  • iot

Start with the control loop

The control loop is: measure soil conditions, evaluate a rule, drive a valve through a protected output stage and publish state for monitoring. Each boundary must be testable.

The ITHutir Smart Irrigation Starter Pack is still a draft, so this article describes architecture rather than claiming a completed hardware build.

Hardware boundaries

The planned system uses an ESP32, capacitive soil-moisture sensor, DS18B20, normally closed solenoid valve, driver and gravity-fed water source. Valve voltage, driver sizing, protection, plumbing and supply behavior must be verified on the actual hardware.

  • Controller: verified ESP32 board with enough I/O for the selected sensor and driver.
  • Moisture sensor: calibrate in the real growing medium; do not copy generic percentage thresholds.
  • Valve path: normally closed valve plus correctly sized driver and protection.
  • Power/water: verify supply voltage, current, grounding, plumbing and gravity-head behavior.

Software and Home Assistant

The ESP32 can own sensor acquisition and safe actuator logic while MQTT carries state and commands to Home Assistant. Calibrate moisture thresholds from the real sensor and growing conditions before enabling automatic watering.

  • First verify sensor acquisition without operating the valve.
  • Then verify the driver and safe OFF state with the actual load.
  • Only after both boundaries pass should MQTT/Home Assistant automation be enabled.

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