# Serin Controller quick start

> Set up your Serin Controller: check compatibility, choose firmware, connect to CN105, and finish setup in your smart-home app.

Source: https://serin-labs.com/setup.html
Last updated: 2026-10-27

Set up a new controller, or follow [Serin Link setup](https://serin-labs.com/controller/link.html#link-only) for control without an app. Read [how it works](https://serin-labs.com/controller/overview.html) for an overview.

**Continue an existing setup**

Install it in the indoor unit, then finish setup in your app. Skip Wi-Fi or pairing steps you completed in the flash tool.

## 1 Check compatibility and gather what you need

[Check your indoor-unit model](https://serin-labs.com/compatibility.html) and confirm its CN105 port is available.

Important

**Already have a thermostat?** Its receiver or adapter may be using the indoor unit's CN105 port. Serin Controller needs exclusive use of this port, so check the existing connection before installation. See [compatibility with existing controls](https://serin-labs.com/compatibility.html#faq).

- **Hardware:** one controller and CN105 cable per indoor unit, plus a USB-C data cable for flashing.
- **Computer:** Chrome, Edge or Brave for the browser flash tool.
- **Control:** your app and its required hub or Home Assistant installation, or a Serin Link. Check the setup route for requirements.

The assembled controller is ready for you to flash. For DIY builds, see [supported boards and parts](https://serin-labs.com/parts.html).

## 2 Choose and install firmware

[Choose the firmware for your smart-home app](https://serin-labs.com/controller/firmware.html), then use the [browser flash tool](https://serin-labs.com/flash.html). Flash with the controller disconnected from CN105 and powered only by USB. The tool can also help with Wi-Fi and show pairing codes.

**Already flashed?** Continue to installation. Use the [update guide](https://serin-labs.com/controller/updates.html) for routine updates.

## 3 Install the controller in the indoor unit

Warning

**Power off at the breaker** before opening the unit. Leave power off until the cover is back on.

Follow [the installation guide](https://serin-labs.com/controller/install.html) to connect CN105, position the controller, replace the cover, and restore power.

## 4 Connect your app or Serin Link

Follow the guide for your installed firmware, skipping Wi-Fi or pairing steps already completed.

[Home AssistantJoin Wi-Fi and adopt the ESPHome controller.](https://serin-labs.com/esphome/setup.html) [Apple HomeJoin Wi-Fi and pair the HomeKit-compatible controller.](https://serin-labs.com/homekit/setup.html) [Google Home, Alexa & SmartThingsAdd the Matter thermostat from your app; it supplies Wi-Fi credentials.](https://serin-labs.com/matter/setup.html) [Serin Link without an appPair Serin Link with your installed controller and check control.](https://serin-labs.com/controller/link.html#pair)

## 5 Check that control works

Check that your app or Serin Link reports the room temperature, then change the mode or target temperature and confirm the indoor unit responds. If it does not, follow [CN105 troubleshooting](https://serin-labs.com/troubleshooting.html#hvac-no-response).

Repeat for each indoor unit, using distinct room names. Continue with [use and configuration](https://serin-labs.com/controller/manual.html#use).