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A smart thermostat for your Mitsubishi mini-split.

The Serin Controller is a Wi-Fi board that plugs into the CN105 port inside your mini-split. Set the temperature from your phone instead of the remote, with everything local: open source firmware, no cloud, no subscription.

Buy Now from $35 Build it yourself
  • 5.0 · 16 reviews
  • Free US shipping
  • Open source on GitHub
The Serin Controller, a compact Wi-Fi controller board with the CN105-to-Grove cable attached

I use Apple Home

HomeKit-compatible firmware pairs straight into the Apple Home app. Siri, scenes and automations, no bridge.

See it in Apple Home

I use Home Assistant

ESPHome firmware, curated configs, and a YAML generator. Every mode, vane and sensor lands as an entity.

See it in Home Assistant

I use Google Home

Beta

Adds the unit to Google Home, Amazon Alexa or Samsung SmartThings as a thermostat, with voice and routines.

See it in Google Home

Running in about fifteen minutes

  1. Check your model

    Nearly every Mitsubishi indoor unit since 2010 has the port.

  2. Flash in the browser

    Plug in over USB, pick your platform, wait two minutes.

  3. Plug into CN105

    Turn off power at the breaker, seat the cable, place the board inside, and restore power.

  4. Add it to your home

    It appears as a thermostat in Home Assistant or the Home app.

Check your model Read the full setup guide →

The lineup

One per indoor unit, or one Multi-Zone for the whole system.

Serin Controller

Pre-assembled, no soldering. Add the wireless room sensor to control from the temperature where you sit.

Buy →

Serin Link

Soon

A rotary knob display that sits on a desk or shelf. Pair it with a Serin Controller (or any ESPHome climate device) and set temperature and mode without a phone.

See it →

Multi-Zone Pro

Soon

M-, P- and City Multi systems: every indoor unit controlled, plus full diagnostics. Works with Home Assistant, Apple Home, Google Home and Alexa.

See it →

Why the CN105 port beats the alternatives

Cloud adapters cost around $180 and stop working when the vendor's server does. IR blasters send commands blindly, with no feedback from the unit.

Serin Controller Cloud adapter IR blaster
Cost from $35 assembled · ~$18 DIY ~$180 ~$15
Feedback Real-time, two-way Via cloud, delayed None at all
Works offline Yes, 100% local No Yes
Firmware Open source Proprietary Varies
Serin Controller
Cost
from $35 assembled · ~$18 DIY
Feedback
Real-time, two-way
Works offline
Yes, 100% local
Firmware
Open source
Cloud adapter
Cost
~$180
Feedback
Via cloud, delayed
Works offline
No
Firmware
Proprietary
IR blaster
Cost
~$15
Feedback
None at all
Works offline
Yes
Firmware
Varies

For multiple indoor units, each has its own port and needs its own controller.

Check your model → Buy Now from $35