The "panic" sign (four people with their arms in the air) is the Beomasters way of telling you, that you asked it to do something it can't or doesn't understand.
Like if f.e. keying in a wrong time or if you try to switch signal source on the Beomaster while the Beocord is recording.

Martin

Thanks, Martin, for the info!

ThomasF wrote:

Thanks Martin - then I know! A bit hard when I never had a chance to use a working BM6000 and try to implement the firmware just from the schematics and wild guessing ... 😕

Indeed, that can lead to a lot of trial and error versions of the firmware. But you could always ask the coder who programmed the BM6000, Arne Rohde!
Well, to start off, you might just want to read his blog https://beomikro.wordpress.com/

I just tripped over this today by accident and for a coder it's incredibly informative - particularly the info on the remote control and data link.
If your Danish is just as rusty as mine (in other words, if your Danish does not extend much beyond the word "smørrebrød" 👍 ) you can run it through Google Translate, which does a very good job with this!

Just a sample from the BM6000 section:

The first development project where I was given the freedom to write a program all over again was Beomaster 6000, where Lars Friis Østergaard developed digital electronics and was responsible for programming.
[...]
However, the program came to resemble the others with a timer interrupt routine performed every 1.04 ms to read remote control input, link input and output, keyboard input, display output and the like. And then a main program like a long loop to take care of all the things that were not so time-critical.

Thousands thanks manfy!

Wow - yes that was a wonderful site! I had not seen it before - and as a Swede I have no problem to read Danish! 😕

I will surely read the chapter about the remote control and the datalink before I start to try to implement it!

Cheers,
Thomas

Hello Thomas,

Nice job ! Hope you get all the functions back in working order with your firmware.

I believe your BM6000 does not implement the "new" datalink (86) , but rather the older version ( someone correct me if I am wrong ).

I have a Beosystem 5500, which implements both, the "old" version between the beomaster and the beogram / beocord, and the "new" version between the beomaster and the auxiliary devices ( speakers, remote, etc ... ).

I have spent some time reverse engineering the "old" protocol, as I could not find any documentation for an old project of mine.

This was a first attempt at making a datalink-enabled bluetooth receiver, but the chip I used turned out to only support the lowest quality bluetooth codec.

Anyway, I gathered some knowledge about the "old" datalink protocol, you can find all my notes in my project git repo : https://gitlab.com/Pilatomic/beobridge/-/tree/master/datalink

Keep up with the good work !

pilatomic wrote:

Anyway, I gathered some knowledge about the "old" datalink protocol, you can find all my notes in my project git repo : https://gitlab.com/Pilatomic/beobridge/-/tree/master/datalink

Keep up with the good work !

Hi pilatomic!

Thanks for your comment! I will surely be helped by your comments and notes when trying to implement the datalink.

I also previously got a link to another github project where an Arduino is made to receive the datalink commands. Since I don't (at least yet 😕) have any compatible B&O devices I will setup one Arduino or ESP8266 as a receiver on the datalink to verify the implementation.

Thanks all for good comments and information - I will update with more information on how I manage to go on! At the moment the code is a bit messy (a lot of hacks for testing and prototyping) and I need to fix the led to be able to get correct values on the display - new leds are on its way 🙂.

Cheers,
Thomas

pilatomic wrote:

Anyway, I gathered some knowledge about the "old" datalink protocol, you can find all my notes in my project git repo : link

Excellent job, pilatomic! I guess you have been spending quite a bit of time testing and analyzing those signals.
Looking at your conclusions in the data.txt file, I'd assume you have gotten those results by analyzing a BeoCenter amplifier and not just the BeoMaster 6000. The commands available on BM6000 seems limited to 37, whereas BeoCenter systems used an extended version of the "old datalink".

I read a bit more in Arne Rohde's blog and there's really lots and lots of interesting info and background in there.
If you're in a hurry, Thomas, all you need to read is the beginning of the remote control page (https://beomikro.wordpress.com/fjernbetjening/) and Tom Jelsing's preliminary datalink draft from 1979 (https://beomikro.files.wordpress.com/2020/11/datalinkprotokol.pdf) and you know pretty much all there is to know for programming the BM6000 remote control and datalink! (page 7-10 of the pdf-file says it all!).

The only thing that's still open is how they mapped a few remote control buttons to that protocol from '79. (My guess is that Vol10/Vol30/Vol50 buttons are mapped to P7/P8/P9 respectively, mute button is probably mapped to 'FILT' and P and RESET are mapped to 'balance<', 'balance>', and/or 'NOINP')
This can be measured with a logic analyzer or digital scope on pin 13 (datalink) and pin 14 (remote) at the CPU (or with the Arduino project mentioned above) .

manfy wrote:

I read a bit more in Arne Rohde's blog and there's really lots and lots of interesting info and background in there.
If you're in a hurry, Thomas, all you need to read is the beginning of the remote control page (https://beomikro.wordpress.com/fjernbetjening/) and Tom Jelsing's preliminary datalink draft from 1979 (https://beomikro.files.wordpress.com/2020/11/datalinkprotokol.pdf) and you know pretty much all there is to know for programming the BM6000 remote control and datalink! (page 7-10 of the pdf-file says it all!).

Wow, thank you very much for the link, that blog is a gold mine !

Deciphering it (I do not know danish), especially the PDF, and discovering that it matches my reverse engineering effort is awesome !

pilatomic wrote:

Wow, thank you very much for the link, that blog is a gold mine !

🤒 Absolutely!
Readers shouldn't expect ready-to-use child-proof details but all the bits and pieces of information are a treasure trove for every hacker or reverse engineer who's been pondering over details of the remote control format, ML, MCL, datalink and so much more!

pilatomic wrote:

Deciphering it (I do not know danish), especially the PDF, and discovering that it matches my reverse engineering effort is awesome !

🙂 Google Translate is your friend! Deciphering the handwriting in those files, however, is a different story altogether...  😎

Maybe this - in english - could be of interest:

Thanks, Millemissen. But that's the datalink '86 version and considerably different from the "old" datalink version and therefore probably not directly applicable in the case of the BM6000.
Additionally, readers should pay attention to the magic words on the first page: "arbejdspapir, der er under stadig udvikling", i.e. it's an internal draft version of datalink '86 and may not represent the official, final version that was implemented in products from 1986 onwards.

Nevertheless, it is extremely useful for analyzing the structure and command codes of datalink '86 and goes well beyond the formally published description of that protocol.