Controller

In electronics and computing, a controller is a device or software component that directs the operation of other devices or systems. It receives input — from sensors, user interfaces, or higher-level software — and produces output that governs actuators, motors, or other hardware. Controllers range from simple dedicated chips (such as a motor driver or a display controller) to programmable microcontrollers that run custom firmware to manage complex behavior.

A microcontroller is a compact integrated circuit that combines a processor, memory, and programmable input/output peripherals on a single chip. It is programmed to execute a fixed application, such as reading a temperature sensor and switching a relay, without needing a full operating system.

In This Home

The term appears in two distinct contexts. The Enphase IQ Gateway acts as a system controller for the solar installation — it monitors microinverter output and manages communication between the rooftop hardware and the cloud. Separately, ESPHome-programmed microcontroller boards are deployed around the home to control sensors and actuators: reading temperature and humidity, detecting motion, and switching devices based on automations in Home Assistant.