IBUS Interface for BMW cars.
|USB Stick version available:||...as well as the "good old"
Com-Port RS232 version:
Hello all BMW IBUS freaks!
Here's my 4th and 6th Version of the IBUS Interface board for IBUS to RS232 or USB interface.
This Interface enables you to connect any device that has a RS232
serial or USB port to the entertainment system of your BMW.
The IBUS controls almost all "non vital" entertainment devices like audio system, telephone, air condition, navigation units, lights and more.
There's an excellent overview of the IBUS here: http://www.openbmw.org/bus/
Since openbmw.org does not exist enymore, but I found a copy here:
(copy of) http://www.openbmw.org/bus/
For further reading please refer to the
HackTheIBUS, the No1 source of information about the IBUS.
I recommend reading the excellent documentation " IBUS Inside" from Franck Touanen, available as pdf on that site in the "Files" > "IBUS Literature & Doc" section (link). Note: you must be registered to download this, it's free. Attention: It can take up to 8 weeks until your membership will be accepted!
I was asked several times for an USB solution; well here's the whole story:
In 2004 I tried to use a simple USB-Serial adapter but it didn't quite work reliable.
Later I found that the silicon used by most of those adapters is not quite 'state of the art' and there were problems with the stability of the required device-drivers as well. Some drivers even prevent standby (S1-S2 Mode) of your computer.
I found that all of them used a ceramic resonators like this. Those resonators have a very limited accuracy (typically +/- 0.5%) and are technically out with the USB specification.
Temperature drift is also a huge problem with ceramic resonators so I decided this is a real 'no go' in a car environment. Especially here in Europe where you find anything from 'deep-freeze' and 'glow heat' temperatures.
A crystal oscillator has an accuracy of 30ppm (= +/-0,003%) and about the same factor for temperature drift. This is well inside the specification over the whole temperature range found in the car, so probably the rest of your system like hard disks and CPU cooling will become the problem then.
The FTDI chip is one of the most advanced USB-Serial controllers on the market today, and device drivers for this chip are already in the box with popular operating systems like Windows XP etc.
The unit is 100% Plug and Play and will be detected as USB Serial Adapter when you plug it in under Windows XP.
When the interface is installed, it will simply show up like any other COM port on your system, so all popular software found in the links section will work like my other stuff for the COM Port. If you use other systems than Windows XP you can always download drivers from the FTDI website here (even Linux and Mac ;-)
More information about how to install the USB driver can be found here.
Unlike other designs this interface is dual-powered.
The USB to serial converter is powered by the USB bus itself, so you
do not need any power from your car to make your computer detect the
I found this more convenient since the IBUS interface part itself can then be powered by a switched or non-switched power source from the car and the USB Interface will be there whenever the computer is turned on.
Since the USB interface part is powered up whenever your computer starts or resumes from standby the interface will always be there, reducing problems with recovery from standby, and sequence of powering up your system.
Of course the new interface also has the NTSC switch onboard, making the interface a one-stop solution for controlling IBUS and video switch in one interface. The NTSC switch will allow you to control the video-input of your navigation screen. When the software switches to the "rear view camera", the navigation system will use the NTSC input and you can inject an NTSC signal of your Car-PC then. This output can connect directly to the navigation system, no need for an relays or anything else.
So finally here it is: A brand new V6 USB interface!
Of course i will continue to offer the good old V4 RS232 Interface. Whenever you have a COM port available in your car computer I'd still go for the RS232 solution, since the interface has less components and does not require USB drivers (even if included with Windows XP).
Note: Though most of the BMWs have an IBUS the brand new models might
have an M.O.S.T. ring instead of an IBUS.
You can find out if your model has an IBUS or not here and here (must be a member of the HackTheIBUS forum to see the database)
The interface is based on a Melexis TH3122 chip that implements
perfect collision detection.
Collision detection is very vital for talking and receiving to the IBUS.
Some "cheap" interfaces on the market don't provide collision detection and therefore can't guarantee reliable transmission and reception.
This interface is compatible with all of the wonderful software out there to turn your BMW into a true Multimedia center:
old friend Bengt-Olof Swing built a really advanced Multimedia Car-PC
you should really look at this!!!
Also please note the excellent products from CarCPU INC: www.carcpu.com
Since the TH3122 is available in SMD only, I decided to make an easy
to assemble PCB.
With the solder-stop mask and the TH3122 being the only SMD part it's fairly easy to solder that part.
However the new Version 5 has that extra FTDI chip and is very hard to solder.
About half of my customers that bought a V5 kit burned or burried the chips under solder.
Therefore I do not offer the V5 at all anymore.
The PCB is 100% electronically tested and absolutely free of any defects.
For those of you not living in the EU and can't transfer money
to my bank (at least at an affordable fee) I will offer PayPal as well.
Sorry, but this is a non-commercial project, I'm not making a big deal of money out of this.
I can't afford to stock expensive boards and chips when I only can use the one I already have.
I also do NOT offer generic
IBUS support of any kind, besides the interface itself.
The circuit will support the CTS and DSR signals for handshake.
So if you simply implement or enable RTS/CTS handshake in your software you have
complete collision detection and will never loose a byte in transmission again.
You can find prices, availability and order online here:
For additional questions ask me.
You can click on the images for larger views.
|Here's the brand new USB Stick Version 6!
It's a complete new design.
A USB Stick that you can plug into your PC and have an "IBUS plug" to connect to your car.
You can see that there's a plug with 4 wires on the back side of the stick:
The cable can be detached easily if you remove your Laptop / PC from your car.
The unit ships with a 50cm (20") cable
to connect to your car
Eagle3D, I was able to get a good impression of the board
even before the prototype was built.
Here's the good old Version 4 board!
Available as a kit including all components
you need to build a RS232 Interface.
Ready assembled board V4.
Interface to the car is the
Yet another view V4
|And the schematics:
This is Version 4
|This is a nifty free service
that tracks down visitors by geography
You should see a flashing dot for each user that is currently browsing this page
It's installed on March 20, 2008 so you do not see all the countries that I ever shipped to so far.
I have shipped to almost any country worldwide that has streets and BMWs ... ;-)
Double click the image to see a larger map and find out more...