Hello guys!

I'm in the middle of a project to emulate an I-BUS (BMW's owm protocol) cd-changer using an empeg: the software is 80% done (working on my laptop), and I now need to port it to the empeg (with the help of a chrooted Debian Potato installation).

One of my greatest issues is to get a line output like RTS to control collision-detection ciruit of the I-BUS interface: nothing too fancy, just a way to turn on/off any logic output would be ok.. I will adapt the voltage if needed.

Any of you have any tips? Please help an empeg customer to enjoy his music inside a car without a DIN adapter

This project, when finished, will be published on the web with all relevant software released under GPL.

I can't really help you out, but just wanted to say that that sounds like a really cool project. I'll be interested to see how it turns out.

Any serial (internal/external) will do: also, as the BMW dashboard already have a radio, I no more need the empeg external tuner (maybe I will sell on ebay one time.. )

BTW: What ttyS device uses the radio? Is the pinout available?
If you (or other guys) can give me a clear path to drive a digital signal out of the empeg, you will make my day

I can't help immediately with your digital output requirement, but I will be very interested in this. I have just bought an E36 M3 which as I understand it has an Ibus CD changer. If I could control the empeg with the standard radio that would be cool since I'm loathe to start hacking away at the dash of my $50k car.

I assume you have an E46 (3 series) or E39/34 (5 series)? Are you getting track titles etc on the head unit/on board computer? I don't think this will be possible with my E36 but I will be investigating.

What do you actually need the digital output for? As I understand it Ibus is merely 9600 baud async serial.
Edit: I see why now. I wasn't aware of this requirement in Ibus.

Hello Shonky, yes newer E36 should have I-BUS and some version of BMW car-audio: my E46 (3-series, of course) have the 4:3 LCD for navigation, on-board computer, radio tuning and so on.

Unlike what has been done with Phatbox (that's a rather "simply" design with just basic CD-changer interface made by 3rd party company and no text display), I want to use my Empeg for better performances, integration & technical excellence.

I just have to code a daemon to "drive" (via I-BUS) the present player software (that works just fine) exploiting excellent Hijack kernel features.

I hope someone can give help to sortout how to get an additional output gate.

BTW: Anyone has disassembled the firmware in TV module? Reverse engineering of the module will be the project following this one I hope to finish soon.

Also, the tuner connector wires are unbuffered TTL - try to pull too much current or short them out and you could cripple your Empeg.

Only thing I can think of so far for an output is the power antenna wire of the tuner. That's a fair waste though and even then it's speed of switching mightn't be good enough. You really need a direct IO from the CPU for this to work properly I would say.

I think the tuner interface is the best option for a possible digital output. As I don't intend to remove the factory headunit, I won't require a tuner anyway.

Thank you a lot mdavey: do you know if GPIO_GPIO24 is really wired (on serial port on the rear) to RTS according to empegcar.h?

Also what's the meaning and the levels of "level" and "signal" signals on the radio module?

I think that's pretty right. I think the level line is merely an analogue signal representing signal strength.

The signal line is as mdavey said, the FM multiplex signal to the DSP which then splits it up to left, right and RDS. Not sure where AM fits in there though.

If you're willing to hack your empeg, trace the microphone wire through the docking connector, and snip it carefully on the internal harness. I'd advise not snipping too close to either connector so that you could resplice it later if need be. Patch the wire to an appropriate internal connection. Someone has already suggested a GPIO. Carefully remove the microphone wire from the harness and replace the appropriate pin with one wired for your use. All at your own risk of course.

The player's serial port is DCE so that it can be connected with a null modem cable to a PC (which are usually DTE). The sled connector on the other hand is a modified DTE with only TX and RX brought out. Pin 4 (usually DCE Ready) has the amp remote line on it. This is 12V switched with the VFD screen - ie, if the VFD is on this is 12V. You cannot control this separately.

MK2a
The signal lines on the serial connector are driven from the GPIO lines of the StrongArm, via an RS-232 driver (a Maxim MAX3241 chip), a thick-film resistor array (a Bourns 4420P chip) and some other minor components. Some of the lines perform other roles when the player is in DC mode (typically, when in a car).
Code:

---

      Serial     GPIO   SA   Other Uses

============================================

   1   DCD  [in]   27   51   Telephone Mute

   2   RD   [in]    -    -

   3   TD   [out]   -    -

   4   DTR  [out]  23   55   debug LED?, MK2 SIR endec speed sel 1

   5   GND

   6   DSR  [in]   21   59

   7   RTS  [out]  24   54   MK2 SIR endec speed sel 2

   8   CTS  [in]   22   56   Headlight Sense

   9   GND*

---

Notes
DTR is sometimes called DTS
DCD is normally called CD
SA is the pin on the StrongArm upon which the signal is present
*As far as I can tell, pin 9 (normally ring indicator - RI) is grounded.
I couldn't work out where pins 6 and 15 of the 4420P go, nor pins 8 and 15 of MAX3241. Pins 1 and 10 on one side of the 4420P and pins 11 and 20 on the other side seem to be connected to their respective grounds.
I am unclear on whether pins 2 and 3 should be swapped, see this thread.

mdavey: thank you (again) very much for your support.

Both DTR & RTS are present on the "rear RS-232" and works quite well: the only thing I had to do was to patch the kernel in order to:

1) Disable the SIR setup (this was causing your problem of sudden level change during kernel operation)
2) Modify a bit get_serial_info & set_serial_info in order to enable a minimum set of ioctl needed to work with DTR/RTS from my user-mode daemon

Today, 0:40 my dashboard saw for the very first time a cd-changer that was - actually - the empeg.

The fun part of the whole project is that since 10 minutes, thanks to an enhanced interface, I don't need any RS232 output (apart the TX signal of course) anymore :-O

Let me some days to sort out various things and to refine various patches and I'll release everything on a site as promised.

Cool!

Although my BMW is a bit different, I'll be interested to see what I can do with mine then. I don't think I'll be able to display song titles though

Quote:
The fun part of the whole project is that since 10 minutes, thanks to an enhanced interface, I don't need any RS232 output (apart the TX signal of course) anymore :-O

Surely you still need to both transmit and receive? Or are still controlling the empeg by it's front panel/remote and ignoring what the interface sends to it? I would have thought you would need to respond to interrogation commands so the main display knows the CD changer is actually there.

BTW: What are you using for an IBus interface? I'm going to have to get/make one me thinks... At least to see how far I can go with my setup.

Edit:
Nevermind. I see your posts on the HackTheIBus list referring to your use of Rolf Resler's interface here

Correct. "Apps use serial" hijacks the serial port away from the player application and allows other applications to open it. "notify=1" exposes the /proc/notify interface, and "suppress_notify=1" prevents the player from outputting track information to the port. Thinking about it, you probably don't need "suppress_notify=1" once "Apps use serial" is set - all the player serial output is being redirected to /dev/null anyway.

Well I knocked up the "simple" interface version last night which should be good enough since nothing else in the car is Ibus ( )

Also I can't do track titles or anything fancy it seems ( again). I was thinking of a remote display although that will of course require a second serial port I don't have. It's certainly going to require some creativity on my behalf to keep the stock stereo. For now I think I will simply run the empeg into the changer inputs and I can probably work out how to send all the front panel buttons using the disc select options.

How long before you show us what you've got do you think?

Otherwise I think I'll start writing something tonight assuming I can get a development environment up and running.

Okay, I nominate this effort as "Cool Hack of the Month!"

Awesome, dude!

not to threadjack but anyone know of similar efforts for Pioneer CD changers? I've got a 6 discer in the dash on my new car and it has line level stereo outs.. just gotta do track/disc change control.

does anyone know the name of their bus so i could google some?

Cool project. How are you controlling the playlist interface?

I'm not aware of a Pioneer version but it probably exists. Remember we are trying to make an empeg look like a CD changer to a standard head unit. We aren't trying to drive a CD changer with an empeg although in this case it would be quite easy due to the IBus used in BMWs.

As for controlling playlists (my take anyway), I plan on mapping the 1-6 buttons onto the buttons to control the empeg. Then I think a remote display and an IR extender for complicated stuff.

I already have next/prev track type stuff working, although the headunit is muting things for some reason since I'm not appearing exactly how it expects the CD changer.

I'm completly destroyed: as I'm "self-emplyed" (or something like this) I have to work hard during the day and the only "spare" for developying is during night :-O

Anyway this night (just back from my night-car-fever) was the one! Even if the LCD-display just say CD01-1 (sending messages to various regions on the dashboard-LCD is really easy, I'll do later), my empeg (already mounted with the self-made adapor in the same bay of the original cd-changer) was emulating a BMW I-BUS player, reacting to various dashboard/steering buttons!).

The remaining problems are:

1) Using +12V/GND from the original cd-changer connector (the one that also has the I-BUS signal), I can haar the alternator in the speakers (!). I hope it's a not-so-good-ground problem, I have to investigate further.

2) I used the Mark Lord tip (thank you for replaying) to control the standard player by Empeg guys (using /proc/empeg_notify interface), but it seems that "button=pause" will not do the right things if issued in a odd number order (I hope you get what I want to say, I'm too "underslept" to speak a more decent english. Sorry.

3) I see that "long key press" means a fixed hold/release sequence in the kernel. I don't know if it's a good thing(tm) to patch hijack.c in order to accept a release signal via an ioctl (I want to implement a decent FF/REW).

4) Maybe, when I finish the daemon that deals with the I-BUS, I could think to swap also the player software (the original software eat a lof of CPU, and I think I don't need anymore most of the original features): what alternative (and open source) player do you suggest? Squash looks good, but don't seems actively developed anymore.

BTW for all BMW-guys: Remote signal (= red input for the empeg) is on white wire on radio signal connector (the box under the cd-changer and the tv-tuner if you have one). The signal is delayed of about 1 minute when you turn off the engine.

I could write more and more things, but I'm completly destroyed and I really have to get some sleep.