Description
This project provides a DIY electronics kit for Mercedes-Benz vehicles equipped with the AIRmatic air suspension system.
It enables the individual adjustment of suspension level by manipulating the level sensor signals (0.5V – 4.5V range) by up to ±1V.
Separate level settings can be configured for different driving modes (Comfort, Sport, Sport 2).
Disclaimer
This project is published solely as an informational DIY guide for private, non-commercial use.
No products, kits, or components are sold, supplied, or placed on the market.
The author does not act as a manufacturer, distributor, or operator placing products on the market under applicable product safety laws (such as EU Product Safety Directive or national laws).
Use at your own risk. No warranty is provided.
This modification is intended for motorsport or off-road use only and is not approved for use on public roads.
Installing this modification may invalidate your vehicle's operating license and type approval, and may be subject to local laws and regulations.
The user assumes full responsibility for any legal consequences, including but not limited to liability for safety, damages, and compliance with regulations.
License
This project is licensed under the MIT License.
See the LICENSE file for full details.
This project includes third-party libraries licensed under the LGPL-2.1 license.
In accordance with the LGPL-2.1 license terms, please always provide full source code with every binary released.
Credits
-
Concept and development
Project Author: aIecxs -
MCP2515 Arduino Library
Library for SPI communication with MCP2515 CAN controllers.
autowp/arduino-mcp2515 -
Mercedes-Benz CAN Bus Research
CAN bus reverse engineering by @rnd-ash.
rnd-ash/mercedes-hacking-docs -
ArduinoJson
Efficient JSON serialization library for embedded systems
bblanchon/ArduinoJson -
ElegantOTA
Library for web-based OTA firmware and filesystem updates
ayushsharma82/ElegantOTA -
ESPAsyncWebServer
Asynchronous web server for ESP32
ESPAsync/ESPAsyncWebServer -
AsyncTCP
Asynchronous TCP library for ESP32 (dependency of ESPAsyncWebServer)
ESPAsync/AsyncTCP -
The Mbed TLS Contributors
Mbed-TLS
UNDER DEVELOPMENT – CODE BASE FOR PERSONAL ARCHIVING ONLY
Offset Voltage
(Duty can adjusted from WebUI calibration)
| PWM | Res | Duty | mm | Offset Voltage (V) |
|---|---|---|---|---|
| 0% | 255 | 0 | -50 | -1.0 |
| 5% | 255 | 11 | -45 | -0.9 |
| 9% | 255 | 23 | -40 | -0.8 |
| 14% | 255 | 34 | -35 | -0.7 |
| 18% | 255 | 46 | -30 | -0.6 |
| 23% | 255 | 57 | -25 | -0.5 |
| 27% | 255 | 69 | -20 | -0.4 |
| 32% | 255 | 80 | -15 | -0.3 |
| 36% | 255 | 92 | -10 | -0.2 |
| 41% | 255 | 103 | -5 | -0.1 |
| 45% | 255 | 115 | 0 | 0.0 |
| 50% | 255 | 126 | 5 | 0.1 |
| 54% | 255 | 138 | 10 | 0.2 |
| 59% | 255 | 149 | 15 | 0.3 |
| 63% | 255 | 161 | 20 | 0.4 |
| 68% | 255 | 172 | 25 | 0.5 |
| 72% | 255 | 184 | 30 | 0.6 |
| 77% | 255 | 195 | 35 | 0.7 |
| 81% | 255 | 207 | 40 | 0.8 |
| 86% | 255 | 218 | 45 | 0.9 |
| 90% | 255 | 230 | 50 | 1.0 |
| Pin | Signal | Pin | Color | Description |
|---|---|---|---|---|
| 1 | NVLM | 6 | GYVT (grey-violet) | Ground front left level sensor |
| 5 | NVLV | 27 | BNWH (brown-white) | Supply front left level sensor |
| 4 | NVLS1 | 38 | GNRD (green-red) | Signal 1 front left level sensor |
| 6 | NVLS2 | 34 | BKBU (black-blue) | Signal 2 front left level sensor (optional) |
| Pin | Signal | Pin | Color | Description |
|---|---|---|---|---|
| 1 | NVRM | 30 | BNBK (brown-black) | Ground front right level sensor |
| 5 | NVRV | 3 | WHBU (white-blue) | Supply front right level sensor |
| 4 | NVRS1 | 40 | BKYE (black-yellow) | Signal 1 front right level sensor |
| 6 | NVRS2 | 36 | BNRD (brown-red) | Signal 2 front right level sensor (optional) |
| Pin | Signal | Pin | Color | Description |
|---|---|---|---|---|
| 1 | NHRM | 24 | BNWH (brown-white) | Ground rear axle level sensor |
| 5 | NHRV | 27 | BUWH (blue-white) | Supply rear axle level sensor |
| 4 | NHRS1 | 25 | BNGY (brown-grey) | Signal 1 rear axle level sensor |
| 6 | NHRS2 | 21 | YEBK (yellow-black) | Signal 2 rear axle level sensor (optional) |
| Pin | Signal | Pin | Color | Description |
|---|---|---|---|---|
| 1 | NHRM | 2 | BNGY (brown-grey) | Ground rear axle level sensor |
| 4 | NHRV | 13 | BUWH (blue-white) | Supply rear axle level sensor (swapped?) |
| 5 | NHRS1 | 12 | BNWH (brown-white) | Signal 1 rear axle level sensor (swapped?) |
| 6 | NHRS2 | 3 | YEBK (yellow-black) | Signal 2 rear axle level sensor |
| Code | Color (EN) | Farbe (DE) |
|---|---|---|
| BK | Black | Schwarz |
| BN | Brown | Braun |
| BU | Blue | Blau |
| GN | Green | Grün |
| GY | Grey | Grau |
| PK | Pink | Rosa |
| RD | Red | Rot |
| TR | Transparent | Transparent |
| VT | Violet | Violett |
| WH | White | Weiß |
| YE | Yellow | Gelb |
| Prefix | Meaning |
|---|---|
| N | Level Sensor (Niveausensor) |
| V | Front (Vorne) |
| HR | Rear Axle (Hinterachse) |
| L | Left (Links) |
| R | Right (Rechts) |
| M | Ground (Masse) |
| V | Supply (Versorgung) |
| S1 | Signal 1 |
| S2 | Signal 2 |
The printed circuit board (PCB) layout for this project was created using the Maker Edition of TARGET 3001! generously provided for non-commercial DIY use.
With kind permission of IBF Electronic – www.target3001.com
Download full schematic and PCB LM2902N.T3001
This license allows free usage exclusively for personal, non-commercial projects. Redistribution or commercial use of the PCB layout created with this software may require a separate license.
To compile and upload the firmware to your ESP32, follow these steps:
-
Arduino IDE 2.x
Install the Arduino IDE -
ESP32 Board Support
Make sure you have installed the ESP32 board package by Espressif Systems
esp32 by Espressif Systems -
LittleFS support
For file system operations (e.g. storing presets) install the ESP32 LittleFS tool for Arduino IDE 2.x Add-on -
MCP2515 CAN Library
Install the library via Arduino Library Manager: search forautowp-mcp2515
https://github.com/autowp/arduino-mcp2515 -
ArduinoJson Library
Install the library via Arduino Library Manager: search forArduinoJson
https://github.com/bblanchon/ArduinoJson -
ElegantOTA Library
Install the library via Arduino Library Manager: search forElegantOTA
https://github.com/ayushsharma82/ElegantOTA
next open%UserProfile%/Documents/Arduino/libraries/ElegantOTA/src/ElegantOTA.hwith Editor,
⚠️ modify the line:#define ELEGANTOTA_USE_ASYNC_WEBSERVER 1-> change 0 to 1⚠️ -
ESPAsyncWebServer Library
Install the library via Arduino Library Manager: search forESP Async WebServerby ESP32Async
https://github.com/ESP32Async/ESPAsyncWebServer -
AsyncTCP Library
Install the library via Arduino Library Manager: search forAsync TCPby ESP32Async
https://github.com/ESP32Async/AsyncTCP -
FakeCH340 Driver (optional)
If you encounter serial driver conflicts under Windows, you may need to install FakeCH340 drivers.
FakeCH340DriverFixer by SHWotever -
Download and Extract the firmware
download and extract w211-airmatic-master.zip
create new directory%UserProfile%/Documents/Arduino/AIRmaticand copy files- data/*.*
- AIRmatic.ino
- Wireless.ino
- CAN.ino
- w211_can_c.h
- w211_can_b.h
- crypto.h
- crypto.cpp
-
Compile and Upload the firmware (USB)
connect the ESP32 DevKit to Computer, open the Arduino Sketch, select the Board
Tools -> Board -> esp32 -> ESP32 Dev Module
click Upload Icon, press the BOOT button on ESP32 DevKit to enter flashing mode
press[Ctrl]+[Shift]+[P], then type >"Upload LittleFS to Pico/ESP8266/ESP32"
(refer to guide 3. LittleFS support screenshot 4.) -
Update the firmware (WiFi)
connect Computer to ESP32 WiFi (see Wireless.ino for credentials)
visit http://192.168.4.1/update
upload the AIRmatic.ino.bin (or see in%Temp%/arduino/sketches)
select LittleFS, upload the AIRmatic.littlefs.bin (or see in%Temp%->tmp*.littlefs.bin)
-
Location of air suspension ECU and CAN connector X30/6
For 211/219 the control unit is located under right side passenger footwell. (refer to Pinout.pdf for details) -
Power Supply:
Use a DC-DC buck converter (12V -> 5V) to supply power to the microcontroller (MCU). -
Connect PCB to control unit:
Wire battery voltage, ground, and the level sensor signal lines between the PCB and the vehicle's air suspension ECU. For a visual guide on wiring, refer to the following video:
Wiring Overview Example (© RENNtech Inc.) -
Connect MCU to CAN bus module:
Use the SPI interface (MOSI, MISO, SCK, CS, INT) to communicate with the MCP2515 CAN module. For AIRmatic mode selection from center console (CAN C) is splitted from ECU. For Steering wheel buttons (CAN B) second CAN bus module with 16 MHz Crystal Oscillator is required. -
Connect MCU to PCB:
Link the MCU PWM output pins to the PCB for analog signal offset control. (refer to AIRmatic.ino for pins)
- Start engine
- Put Instrument Cluster in Phone mode
- Select AIRmatic mode from center console
- Use the Steering wheel buttons to adjust offset (5mm steps)
- Save Settings with long press
Wireless Usage
- connect to ESP32 WiFi
- visit info page -> http://192.168.4.1/config
(within 5 minutes of start)
