I saw an email from Stefan that was posted to the Audi TT forum a while ago about compatibility with Nav systems. If I understand correctly one would need to build a CAN interface to filter out the Nav system's CAN messages. I've been doing a little sniffing on the bus and the NAV system puts out quite a few different messages. Am I right in thinking that I would only need to filter out the ones that affect the display? As far as I can tell these are the ones with IDs; 0x56F, 0x604, 0x6C0, 0x6C1, 0x6C4, 0x6C5. The first two seem to have something to do with blanking the display and the last 4 seem to be the actual display data. I'm not entirely sure I'm right because the display data seems to be encoded (some sort of compression algorithm?) and I can't make sense of it. Or am I completely wrong?
At the time there was quite a bit of interest in your product but many people have NAV systems in their cars and I think this put them off. If I manage to make a system to filter out the NAV messages I'll post details on the Audi forum board.
Thanks
John Millward