HYMER Connect for Home Assistant
A custom integration that brings your HYMER / Erwin Hymer Group motorhome or caravan into Home Assistant — with 130+ real-time sensors, light control, GPS tracking, solar monitoring, and more.
Repository: github.com/BetaHydri/hymer-connect-ha
What is this?
If you own a motorhome or caravan from the Erwin Hymer Group with a Smart Control Unit (SCU), you probably know the HYMER Connect app. This integration brings all that data — and more — directly into Home Assistant via the EHG cloud’s SignalR WebSocket API.
The entire API was reverse-engineered from the Android app using mitmproxy and a custom protobuf decoder.
Supported Brands
All EHG brands with a Smart Interface Unit (SIU):
| HYMER | Carado |
| Bürstner | Laika |
| Dethleffs | Sunlight |
| Eriba | FreeOnTour |
| LMC | Niesmann+Bischoff |
Features
Light Control
Control 8 interior lights directly from HA — on/off, brightness (0–100%), and color temperature (2700K–6500K) for supported lights. Commands are sent in real-time via the SignalR WebSocket to the SCU. Works remotely from anywhere.
| Group | Lights |
|---|---|
| Living | Ceiling, Ambient, Kitchen, Seating Overhead |
| Private | Bedroom Ambient, Night Light, Bathroom Ceiling, Bedroom Overhead |
Solar Monitoring (v2.5)
Real-time data from the Voltronic MPP260CI MPPT solar charger:
- Panel voltage (V), charge current (A), computed power (W)
- Solar active binary sensor
- Ready for the HA Energy dashboard
130+ Real-Time Sensors
All data streams via SignalR push — no polling delays:
| Category | Examples |
|---|---|
| Vehicle | Odometer, speed, RPM, fuel level, engine hours, coolant temp, gear |
| Battery | Voltage, current, SOC (%), charge phase, charger status, battery type |
| Water | Fresh water level (%), grey water level (%) |
| Temperature | Ambient, AdBlue |
| GPS | Lat/lon, altitude, heading, satellites, signal quality |
| Doors | Driver, passenger, sliding, rear (open/closed) |
| Status | Lock, ignition, handbrake, engine running, headlamp, cruise control |
| Heating | Truma heater: fan speed, setpoint, electric power, fuel type, mode |
| Fridge | Mode, status |
| Alarm | Armed status, battery level |
| SCU | Firmware version, connectivity |
Ready-to-Use Dashboard
A full Lovelace dashboard YAML is included — just paste it into a new dashboard and go.
Screenshots
How It Works
Data Flow:
| Step | From | To | Protocol |
|---|---|---|---|
| 1 | Home Assistant | EHG Cloud | OAuth2 login |
| 2 | Home Assistant | EHG Cloud | Exchange BLE refresh token |
| 3 | Home Assistant | EHG Cloud | SignalR WebSocket (real-time push) |
| 4 | EHG Cloud | SCU in vehicle | Cellular (LTE) |
| 5 | SCU | Truma, Dometic, Victron, etc. | CAN / LIN bus |