Webasto monitoring and controlling with AutoPi


Hi! It’s soon winter again on the northern hemisphere and I’ve been wondering if there’s interest in the AutoPi community for monitoring and controlling Webasto heaters with the AutoPi. I know there are commercial solutions available for remote operations of the Webasto but I already have a simple Arduino Mega 2560 with a LCD display monitoring the Webasto Thermo Top V unit in my car.

The Webasto W-Bus is based on the K-line signal levels so it’s quite easy to interface. I located the six pin Webasto Telestart cable under the dashboard and connected the Arduino to it with the L9637 chip. If your car doesn’t have a connector for the Telestart unit you can also connect to the bus from the four pin Webasto clock connector - and of course one can even connect to the bus directly on the heater connector.

Here’s a video by is0-mick 2015 / mickr1969 where I found the necessary Arduino source code and instructions for the Arduino Mega.

Code for Arduino Mega 2560 by is0-mick 2015

WBUS.H (borrowed from the pic micro version by is0-mick 2015)

My primary goal would be to use the USB ports available on the AutoPi to interface with the Webasto with the libwbus library and a FTDI serial chip. The libwbus is available from Sourceforge and I already have a 15 € USB cable with the FTDI and L9637 chips that works on a PC with the Webasto software. I also have a direct serial cable with the L9637 chip but as far as I know there are no available serial ports on the AutoPi.


The 15 € USB cable I mentioned is available from the OBD2-Shop (it’s a basic K-line adapter cable)


If using the libwbus would fail for some reason on the Raspberry Pi/AutoPI my second option is to interface the AutoPI to my current Arduino Mega board via the I2C bus.

The main delay in this project has been that it’s taken me time to choose between the ESP32 based Freematics One+ and the AutoPi but I think I’m now leaning to choosing the AutoPi. The Freematics community forums are currently full of spam and seem to be mostly inactive. Also there’s even less available external connections (practically none if you install the GPS module) on the Freematics One+ than on the AutoPi. The Arduino Due based Macchina M2 was also one of my options but they’re now developing a PocketBeagle based M2 with no known date for delivery. AutoPi seems to be most ready to market with a vibrant developer community. I hope I’m making the right decision, 275 €… (yes, I want the GPS and GSM)


Status update: I was unable to get the Arduino Mega to work reliably enough for daily use. Lot’s of timeouts and connection problems. So I’ll now forget the Arduino / ESP32 / Freematics / Macchina M2 as an option. Also the 2nd Gen AutoPi dongle looks very good and I’ve been able to fork and compile the original libwbus to an old RPi2.

My fork of the libwbus is now available at https://sourceforge.net/u/auxh/libwbus/ci/master/tree/

Next step: Compiling the libwbus on the 2nd Generation AutoPi dongle and writing some small scripts on top of libwbus / wbtool.