HomeKit-Compatible Firmware Features

Free, open-source firmware you flash yourself. Works with Apple Home through the HomeKit Accessory Protocol (HAP) and includes a full-featured web UI. No third-party bridge or Home Assistant required — just an Apple Home Hub (Apple TV or HomePod) for remote access and automations.

Not MFi-certified — this firmware implements HAP independently and is not a certified Apple accessory.

HomeKit climate control interface — Apple Home — thermostat control

Built-in web UI dashboard — Built-in web UI at http://Serin-XXXX.local

First-boot WiFi setup: connecting to the Serin hotspot and entering home WiFi credentials — First-boot WiFi setup

Climate Control

Modes: Off, Heat, Cool, Auto, Dry, Fan
Temperature: 0.5°C precision with +/− step buttons
Dual Setpoints: Independent heat/cool thresholds in Auto mode, persisted to flash
Fan Speed: Auto, Quiet, Speed 1–4

Vane Control

Vertical vane positions with swing mode
Wide (horizontal) vane positions
Controllable via HomeKit or the web UI

Diagnostics

Compressor frequency
Outside temperature
Runtime hours
Error codes
Sub mode and stage information

BLE Remote Temperature Sensor

Use a Bluetooth Low Energy thermometer placed at room level for more accurate temperature readings. The firmware auto-detects the sensor type from BLE advertisements — no Bluetooth pairing required.

Supported sensors: Govee (H5072, H5075, H5074, H5051, H5052, H5071, H510x), Xiaomi PVVX (LYWSD03MMC, CGG1 with custom firmware), BTHome v2 (SwitchBot, Shelly, generic)
Live status: Temperature, humidity, battery level, signal strength, last update
Feed toggle: Enable or disable sending the sensor temperature to the heat pump from the web UI
Automatic fallback: If no BLE data arrives for 90 seconds, the heat pump reverts to its internal thermistor

Crash Loop Safe Mode

Detects 5 consecutive crashes and enters safe mode
Safe mode runs WiFi and web UI only — skips CN105, HomeKit, and BLE
Allows OTA recovery when the device is stuck in a crash loop
Counter resets after a successful boot

OTA Updates

One-click update check: the web UI compares your running version against the latest published release and installs it in a single tap — no manual download
Manual firmware upload via web UI or curl
SHA256 integrity verification before applying
Automatic rollback if validation fails after update

Web UI

A single-page interface at http://Serin-XXXX.local (or http://<device-ip>) for full control without Apple devices:

Thermostat mode and temperature control
Fan and vane adjustments
Pairing status and QR code
Device settings (name, poll interval, log level, °C/°F toggle)
WiFi network scanner for easy setup
Real-time log streaming via WebSocket

Supported Boards

Board	Status
M5Stack NanoC6 (ESP32-C6)	Supported
M5Stack Atom S3 Lite (ESP32-S3)	Supported
ESP32-C3 SuperMini / XIAO	Not tested
Generic ESP32 DevKit	Not tested

Get started

Flash the Firmware

Use the browser flash tool to install the HomeKit firmware, then follow the setup guide to connect and pair.

Flash Firmware Setup Guide

Source Code

The HomeKit-compatible firmware is open source. See the GitHub repository for protocol documentation, project structure, and build instructions.