Setting Up Your Device

You can control your Mitsubishi mini split HVAC with this device either standalone via a built-in web interface, or integrate it into your smart home setup using ESPHome and Home Assistant.

1. What You’ll Need

Option A: Purchase Parts Individually

Device:
- M5Stack Atom S3 Lite or NanoC6
Cable:
- JST PAP-05V-S connector (CN105 port on the HVAC unit)
- Grove HY2.0-4P connector (ESP32 side)

Option B: Preassembled Kit

Ready-to-go kit including the device, custom cable, and pre-flashed firmware — coming soon.

If you purchase the kit, you can skip wiring and firmware flashing — it's all ready to connect to your Wi-Fi and Mitsubishi HVAC unit.

2. Flash the Firmware

Note: Firmware is already flashed if using the preassembled kit.

Use the YAML generator with ESPHome Dashboard
Or flash a pre-built firmware via ESPHome Web

3. Connect to Wi-Fi

After flashing (or if pre-flashed), power up the device and connect it to your Wi-Fi network using either method below:

Option A: USB C

Plug the device into your computer.
Click the button below to launch browser-based Wi-Fi setup.

Option B: Wi-Fi Access Point

Plug the device into USB power.
Connect to the temporary Wi-Fi network (serin-cn105-XXXX).
If not automatically prompted, go to http://192.168.4.1.
Enter your Wi-Fi credentials.

Once connected, the device should appear in your ESPHome dashboard, ready to adopt.

4. Connect to the Mitsubishi HVAC Unit

Turn off power to your HVAC unit and open the cover to locate the red CN105 connector.
Plug the CN105 connector into the HVAC unit and Grove connector into the device.
Place the device safely inside the unit if needed, reinstall the cover, and restore power.

5. Access Web Control

Visit the device’s IP address in a browser.
Monitor and control your system through the built-in interface.

Disclaimer

Modifying HVAC systems may void warranties and carries risks. Proceed with care. This project is provided as-is, with no warranties or liability.