andylaurence

No. I'm no assembler expert, and I couldn't find any reference to what hardware the code was to run on. I've got a changer in the post, so I suspect I will be starting down the same road you are very shortly. Reverse-engineering protocols - gotta love it!

Cheers,
Andy

mrblau

I will post some info that I have. This might get you started. First column is a timestamp and the second is the hex message sent. From this first log I found that the changer address seems to be 80 and the head unit 0F. Messages end with 4F. The head unit seems to echo eveything the changer sends it, including 4F. The changer echos everything it is sent too, except for 4F.

804801 seems to mean 'use 4800 baud'
804802 seems to mean 'use 9600 baud'

ON - 4800

'sent from changer
30:22.743 80 AD
30:22.763 80
30:22.763 48
30:22.773 01
30:22.803 0F
30:22.813 48
30:22.823 01
30:22.823 4F
30:22.843 80 '\
30:22.853 48 02 '- Change baud to 9600


'sent from head unit
30:22.733 80
30:22.743 AD 4F
30:22.763 80
30:22.763 48
30:22.773 01
30:22.773 4F
30:22.813 0F
30:22.823 48 01
30:22.833 4F
30:22.833 80 '\
30:22.843 48 02 ' } change baud to 9600
30:22.853 4F '/

mrblau

Then at 9600, this is the last of the startup messages, 80A54F means play.

'sent from changer
32:46.780 00 '??? 9600 baud now ???
32:46.790 80
32:46.800 18 06
32:46.830 FE
32:46.860 80 80 18 06 FE 98
32:46.860 00
32:46.870 80 18
32:46.870 18
32:46.950 80 A7
32:47.281 80 A5
32:47.401 0E 08 01 4F
32:50.95 80 A5

'sent from head unit
32:46.780 00 'reckon we are at 9600 baud now
32:46.780 80
32:46.790 18 06
32:46.790 FE
32:46.800 98
32:46.830 FE
32:46.830 80
32:46.840 80 18
32:46.850 06
32:46.850 FE 98
32:46.880 00 80 18 18 FE 98
32:46.940 80
32:46.960 A7 4F
32:47.0 7C
32:47.30 7C
32:47.50 7C
32:47.70 7C
32:47.91 7C
32:47.111 7C
32:47.141 7C
32:47.161 7C
32:47.181 7C
32:47.201 7C
32:47.221 7C
32:47.241 7C
32:47.271 80
32:47.281 A5 4F
32:47.411 0E 08 01 4F
32:50.75 80 A5 4F

andylaurence

OK, this is slightly beyond my knowledge limits at the moment. I've just received my CD changer, so once I get a cable (or work out the pinout), I'll hook up a serial cable to start poking around.

Cheers,
Andy

markcame

I've started to read the thread, i Have a blaupunkt OEM radio on my car and i will make an adapter or controller to enable the aux input on it, but i didnt't know a way to make a reverse engeniering of the protocol because afther i've read some thread and get some advice i relize that it is 9 bit of data and varible speed rate 4800 to 9600... so somethig have a soluscio to start with the protocol, i've also googled about dms protocol but didn't fine anithing of usefull..

microkid

I have been reading this thread with interest as I am currently working on an interface that will fit between the Blaupunkt headunit in my new fiat and my ipod.

This is going to be a fairly extensive modification as I intend breaking the connection between the headunits internal display and either repeat the headunits on display messages or display ipod data there. I also intend doing the same with the dashboard display.

My hardware interface access all functions of the ipod using the Apple Accessory Protocol. I have constructed my own menu and control system that means I only need three buttons to navigate around it. I have also included a alphabetical search.

My problem comes with getting the analogue audio into the headhunt.

Its has an Aux input if you press the CD button twice the display even shows "AUX" suggesting it has been selected, but if I connect up to the aux input pins I get nothing.

I did a similar project for the Alfa 147 which also has a Blaupunkt head unit, and the same aux input connection. I found that by looping TX and RX data connection round I could fool the unit into thinking it had a CD changer connected. However this unit does not respond to that either.

So after reading this thread I am guess I will need to write some code to emulate the CD changer. I will be using a PIC to achieve this.

As I don't have a CD changer I cant reverse engineer this protocol, so it would be great if some could give me some ideas! Does the headunit send a code to look for a response from the changer at power up? Or does the changer send a code to at power up indicating it is present? what is the protocol all I want to do is open the aux input.

However maybe they cant be opened but then why allow AUX to be selected?

Help!

danygate

microkid I'm also a 147 owner, I do want to achive this goal.
please let me know if I can help to make it works!!!!

hooverphonique

any progress on this? the dumps recorded here, what serial setup were they made with (stop bits, parity, etc) ?

on the mictronics page it is mentioned that it is a 9 bit protocol and that the last bit is used for sync.. anybody here knows what sort of sync this is ??(mictronics data doesn't fit with parity or anything like that)

regards,
hoover

hooverphonique

ok.. i made an initial test using a scope (i don't have a cd changer)..
there is definately some 9 bit stuff going on here (as mentioned on mictronics.de), but i don't know if the 9th bit is some sort of sync/parity or an actual data bit.. appears to be 4800 bps as well...

edit: judging from mictronics, it looks like bit 8 is high for the first and last word of a frame, and otherwise low.

microkid

Time for an update / refresh.

I have been trying to figure out the serial coms on the Blaupunkt dms. But as i don't have a cd changer it is proving impossible as I have no idea how it should respond.

I could obviously fire random commands back but I would be there a very long time.

If I had a cd changer i could just T off the serial lines onto my laptop and log all of the communications.

Armed with this information I should be able to make a decent ipod interface.

So couple of questions...

1/ does anyone have an old (but working) Blaupunkt cd changer and lead that will work with the Alfa / Fiat standard fit (i have now turned my attention to the Alfa 937 unit)

2/ does any one have an Alfa GT or 147 Blaupunkt MP3 head unit for sale?