CoolMaker Lab has developed an open-source, Home Assistant-compatible controller for managing cooling in server racks, NAS systems, network cabinets and other equipment enclosures. The ESP32-based board can operate four fans independently while collecting tachometer data and readings from external temperature sensors.
According to CNX Software, the controller runs ESPHome to connect with Home Assistant. That enables fan switching and speed adjustment through the open-source automation platform, while also allowing temperature-based control rules. The hardware is aimed at enclosures where cooling requirements vary with equipment load or where installers need a way to monitor ventilation without using a separate commercial control system.
Four-channel fan management
Each of the four outputs supports a 4-pin PWM fan, with speed adjustment from 1% to 100%. Separate tachometer inputs provide RPM monitoring for each fan, allowing the controller to distinguish between a commanded speed and the fan’s reported operation. Individual power switching can also disconnect a fan completely rather than merely reducing its rotation speed.
- Four independent 4-pin PWM fan connections
- Four tachometer inputs for RPM monitoring
- Individual fan power switching for complete shutdown
- Automatic speed adjustment based on temperature
- Support for up to four external DS18B20 temperature sensors
The power-switching design uses TPS22810DBVR load switches. CNX Software reports that this permits zero-RPM operation when a fan is turned off, a function that may be useful in installations where fans should remain inactive until cooling is required. The board was tested with a 120mm cooling fan and an external DC power supply, according to the report.
| Item | Specification or function |
|---|---|
| Controller | ESP32-WROOM-32-N4 with 4MB flash |
| Connectivity | 2.4GHz Wi-Fi and Bluetooth LE for proxy functions |
| Fan control | Four 4-pin PWM channels, 1–100% adjustment |
| Temperature inputs | Up to four external 1-wire DS18B20 sensors |
| Power | 12V DC input; 12V/2A or higher recommended |
| Software | ESPHome and Home Assistant compatibility |
Expansion options for equipment enclosures
The board includes a USB Type-C connection with a CH340C USB-to-serial converter for programming and debugging, plus a four-pin expansion header carrying 5V, ground and two GPIO connections. The design also includes a web interface and an HTTP REST API, giving integrators and developers additional ways to interact with the controller beyond Home Assistant.
The latest v2.0 hardware and firmware add optional support for the LD2402G 24GHz mmWave radar through UART when compatible firmware is used. The radar option is described as supporting presence-based automation. The board also provides Bluetooth LE proxy functionality through its ESP32 platform, although the extracted product information does not identify a finished enclosure, dimensions or a dealer distribution program.
Power enters through a barrel connector, with a TPS5430DDAR buck converter reducing 12V to 5V and an AMS1117-3.3 regulator providing 3.3V operation. The combination of open hardware, local sensor inputs, network connectivity and Home Assistant support positions the controller as a configurable option for cooling management in custom-built racks and other technical enclosures. CNX Software lists the board’s dimensions as not yet specified.
