ESP32 Mini IoT Development Module with 4 Relays

Take your IoT projects off the breadboard

Meet the ESP32 Mini IoT Development Module — a compact, ready-to-use controller board designed and manufactured by ADIY India. Instead of wiring up relays, drivers and power circuitry yourself, everything you need for real-world automation is already built in and tested.

Product overview

This module is built on the ESP32-WROOM platform, giving you Wi-Fi and Bluetooth LE out of the box, along with support for the protocols IoT projects actually run on — HTTP, MQTT, WebSocket and more.

The board is slightly larger than a standard ESP32 dev board, and that extra space is put to good use: it carries four onboard relays, each with its own screw terminal and dedicated GPIO mapping.

What's on the board

• ESP32-WROOM module — Wi-Fi, BLE, HTTP, MQTT, WebSocket and other IoT protocols

• 4 × high-quality 5V coil relays — 7A switching capability (electromechanical, not SSR)

• Optocoupler-isolated relay drive — low-level trigger operation for clean, noise-free switching

• PBT-extended contacts — pole and NO (normally open) brought out to accessible terminals

• USB Type-C port — used for both power and programming, via the onboard CH340 USB-serial chip

• Power indicator LED — instant confirmation the board is live

Both AC and DC loads can be switched, making the board equally suited to a 230V lighting circuit and a low-voltage DC appliance.

Relay pin mapping

The four relays are addressed directly from GPIO, so there's no I2C expander or shift register to learn:

Relays are active-LOW — pulling the GPIO low triggers the relay ON.