ZBasic Forum

I've just acquired a 2002 BMW. The factory install radio cassette has been repalced with a Sony head unit that understands MP3 and has a USB connector on the front, and bluetooth phone connection etc. all in all more useful. the sony also has an IR remote.

however this new device has meant the steering wheel controls no longer function and i would like to restore this. In its simplest form i can gran the commands off the BMW Ibus and interpret them with say a 328n and the either generate the necessary IR signals, or interface to the IR remote.

There are some commercially available interfaces but none will guarantee working with my sony unit. its not that it won't necessairly work, just no one has tried it. for this reason i am thinking making my own might be a more reliable way forward.

i can buy a IBUS interface IC (TH3122) or an IBUS to rs232 module but i wondered if anyone has done this before ?

thanks

I haven' seen any mention of IBus here. There is a spattering of reverse engineering online and, as you found, a pair of converters - but not a lot about the protocol itself. BMW forums (like http://bimmerfest.com/forum) suggest that the three onboard buses (Dbus, Ibus and Kbus) are brought out to the OBD2 connector (search for "coding" there, the term used to program the vehicle options) - and Navcoder, a popular coding tool, includes a simple interface schematic.
http://www.siegenthaler.co.nz/navcoder/index.htm

I'll be interested in your pursuit.

in the end i found a commercial product for £20 that uses the remote control socket on the back of my head unit. I'll install that tonight and see how it goes.

no piont in reinventing the wheel, though the ibus interface didn't seem too hard as this guy http://www.reslers.de/IBUS/ sells a serial interface to ibus.

FFMan wrote:... i found a commercial product for £20...

That makes the steering wheel switches control the Sony?

yeah the unit enables control of the sony. seems like a lot of head units have a remote control plug on the back these days (usually blue). this interface comes with different leads for several manufacturers. perhaps the control protocol is standard and the leads is just differnet connectors, or perhaps the pic in the box is programmed differently for each car/head combination (seems unlikely)

it gets the volume up/down and scan up/down working. the 2 other buttons don't do anything which is shame but its volume i mostly wanted which works ok.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1439.l2649