MINI radio in my E30 dash

[blalor]

First off, let me say that this looked much better in my head than it does in real life, but I still think it's not awful. It's at least as attractive as every other aftermarket head unit on the market, and the orange lighting is the right shade. :D





I took the radio from an '06 MINI, designed and built a circuit that bypasses the "security" on the head unit and also presents an iPod or iPhone to the radio as a Sirius receiver, and crammed the whole mess into the dash of my '91 318is. The faceplate of the head unit is about 7mm too tall for the opening in the dash bezel, but I couldn't come up with a way to trim it without exposing the guts. Even with the height taken care of, there's really no way to have it sit flush with the bezel. But it works, it sounds good enough for now, and I'm pretty proud of the software and hardware design of the IBus enabler and iPod/Sirius adapter.

I still need to get a converter for the antenna, but that's not terribly high on my list, since the only radio I listen to is NPR and I can get that with my iPhone. Everything else is Pandora or the iPod.

I hope to tap into the speedometer signal and enable the speed-sensitive volume feature of the radio, but first I need to get the heat working so I can actually drive the car!

[bmwman91]

Very cool! So you custom made some hardware to adapt iProducts to the thing as a Sirius device? Pretty sweet! Did you use a microcontroller, or did you find a way to do it electronically? Is the little red PCB in the bottom of the pics your creation?

If you have the CD53 electrical schematics, I could take a look & give some input for the faceplate. I think I saw some schematics for it a while back, and the faceplate connections looked identical to those for the CD43. If that's the case, you might be able to get a CD43 faceplate on there, which you can get flush in the dash. I have a spare "BMW Business CD" faceplate that we might be able to figure something out with. The buttons on the CD53 are a little different, but that isn't a huge deal since they are sent to the main board on the regular digital lines as keycodes.

[Holland]

Might not look so good, but that is still pretty impressive.

[blalor]

Yep, that's my PCB (it's actually purple). This is the board as I was assembling it:


The chip's an Atmel ATMega328P. I started the project using the Arduino environment, but I had to tweak some of the Arduino internals; I'm now trying to find enough time to make it a standalone project. The source is here on GitHub; I don't yet have the Eagle files available, but I will.

I initially started out by trying to find another Dension ice>Link: Plus, an iPod-to-CD Changer adapter that I use in my MINI. They're no longer available, but I bought one off a friend who'd gotten it off eBay, but it turned out to be a dud. All the radio needed was to see a valid signal on the bus… I think I ran across some non-working Visual Basic source that would emulate the Sirius receiver at about the same time and the wheels started turning. Also, the Dension wouldn't charge my iPhone 4, so I could actually make something better while I was at it.

I've had a hell of a time working out the bugs, and still have a couple of small ones (I've used up all of the chip's RAM and flash more than once while sending debug data over serial to my computer), but it's now in my MINI and will get a week-long test on a trip to Canada in a few days.

William, you gave me the CD43 schematic, but I don't think you had the CD53 docs at the time. Has that changed? I'd definitely be interested to see them.

Thanks, Holland! Getting it mounted to the bezel turned out to be quite simple, but I spent a lot of time making it that way. :) This is the least of the visual imperfections in this car. I've got tunes, I've got my iPod, and it's not blue, so I'm happy!

[elmercc]

Impressive!

[bmwman91]

Would you happen to have any links describing the iBus / Sirius comm protocols? I have always been curious about the comm standard that BMW uses in their audio system.

(I'd like to find out what standard the engine controls & stuff spit out to C101 too, but it all seems to be pretty hard to find out on old cars like the E30)

[blalor]

This is as about a complete description as you'll find: http://www.jaroslavklima.com/blog/20...bmworgbus.html
This is decent, too, but is much of the same: http://web.comhem.se/mulle2/IBUSInsideDRAFTREV5.pdf

It's a pretty braindead protocol, reminiscent of LIN, but without the master/slave distinction. 2-way serial over a single wire, 9600-8-e-1. The biggest problem with the protocol is that there's no start byte. To do reception/parsing "right" requires waiting for a pause between messages so you know when a new one is starting. The Arduino abstracts away too much of the USART so I can't keep track of the time between bytes, so I look for messages using the checksum: I read the source address byte, the length byte, and then calculate the checksum. If the checksum's valid, I'll attempt to handle the packet. This approach requires keeping a pretty good-sized buffer, but it generally works fine.

(By comparison, the iPod serial protocol starts every packet with 0xff 0x55; makes it very easy to synchronize.)

The Sirius receiver IBus messages were pretty much undocumented until I started this project. I found someone's VB code, but it was minimal and partly incorrect. I did a lot of Googling and forum-prodding trying to find someone who had done the dirty work, to no avail. Then I realized that a friend of mine with a MINI and the factory Sirius receiver lives about a mile away. I hooked into his car and pulled some logs. The decoded result is this:

https://github.com/blalor/iPod_IBus_adapter/blob/972aaca51fe20b14ef0aa18c900770c1251aca4a/logs/parsed_log.txt

I think the E46 was the end of the road for IBus in BMWs. It died in MINIs with the redesign launched in '07. Newer cars use something called MOST, but I don't know much about it. Supposedly it's using fiber-optics for carrying data and (digital) audio.

My MINI's got a couple of "useless" buttons on the steering wheel; they're enabled when you get the phone kit installed. I want to repurpose them for something, possibly to mute and power off my radar detector. The buttons send IBus messages, so that'll be pretty simple, now.

[e30shmobberr]

not my cup of tea but nice!