thinush

Hi :-)

I have a slow moving project for building a android/rasberri-pi radio replacement for my car.

There is recently more happening around android for rasberri pi that is making the project more viable to work on.

One of my issues I am facing is that I want to keep the sound system (Ampplifier and optical network).
Does anyone know technical details about the optical connection for the sound system?

Is it a standard toslink?
The thing is, for the rasberry I can get an add on board for toslink out.
But would there be a way (passive) to connect it to the sound system? What was done with these chinese android radio installations to connect it to the optical sound system?

Also, any ideas on what sound formats are supported over it? And is communication with the amp done via CAM? Or how is the input channel decided? (Ive never seen the amp).

Anyways any advice knowledge, or references would greatly be appreciated.

Edit:

So I found an image on ebay of the amp:
https://drive.google.com/file/d/0B2o...ew?usp=sharing

It seems there are 2 connections for toslink. (ugh seems I'm wrong)
My worry is selecting the input for audio, but I think that would probably not be an issue.
I will see if I can connect my PC's optical out to it tonight and if sound comes out. I'm assuming though that volume control type things would be done over cam?
Or is volume controlled over the otpical link? (I dont know much about the communication over optical)

Rudeney

It is not "toslink" - it's MOST. It is technically an "open standard", but good luck with a DIY interface.

thinush

I found a local supplier that provides an adapter. Thank you.

My last issue I have left with integrating this is getting details displayed to the speedometer. Ive heard its not possible but i still want to take a shot at it and spy on the canbus communication to see for myself. I still have allot of work to do with the android setup. But unlike suspension sysyems... this is a little more up my alley :-P And less spanners to fall on my face

Rudeney

I think there are some interfaces that display info on the cluster. I don't know of any, but I do know it's possible as there are other aftermarket devices that do (like SmartTop and MidCity's Escort radar detector interface)

megacrazy

I am sure you could spy on the CAN bus and eventually isolate the specific messages. Here's a guy that did just that a long time ago. He provides a list of messages he found along with some software:

http://www.honeysw.com/canproject.php

MOST bus: http://www.volkspage.net/technik/ssp/ssp/SSP_286_d1.pdf

Personally though, I would invest my time in something more worth while. If you have a touchscreen in the car there's no need for old school song displays in your speedometer. I've never even used that feature.

thinush

Thanks for the useful info
I'm waiting to get a canbus module for my pi. This allready done takes allot of the PT away :-D

I'm going to find out more about those items that connect to the cluster.
Thing with connecting with the cluster is I loose more than just music display names.

I believe the GPS travel direction indicator will stop working.
From my understanding I can display more info than just that on there, so it would be useful to do that.

Maybe one day I replace the cluster with a custom job. But that is not in the near future.

megacrazy

No problem. I looked into it before getting started on my HUD project but decided it was too much work for too little gain . I wanted to replace the entire cluster with a digital display version but decided to wait...as the next car I get it's probably going to have a digital cluster anyway...so I'll just mess with that instead.

I remember it not being terribly difficult to send data to the display....but it was a very low level affair. Most of these LCD displays require you to draw the entire thing out so there is no menu structure and you just tell it scroll up and down. You'd have to tell it pixel by pixel what to do. Annoying but doable. Don't forget to post results if you start working on this

thinush

Hehe if the cluster works as you describe that means i can do bearly anything with it :-P
I bought my car lat year with the idea of pc replacement for radio. We will have to see where i get. But i have nearly everything i will need.

megacrazy

Haha you can...it just won't be a pleasant affair.

See if you can get your hands on Kanzi Studio which I think is being used by most OEMs to do their entertainment/digital clusters. If you spend all that time decoding CAN messages might as well put a display in there and design your own gauges.

Adarah

Do I understand correctly that you were able to get the original Harman Kardon fibre optic sound system connected to an after market touch display?

I ask because I have an after market touch display in my CLK that was installed in 2012 (getting a little old in tech years now i know), and I can't get it to connect to the subwoofer in the back because, as I was told, the Kenwood that I have in there can't be connected to anything that uses fibre optics. It is very frustrating as I loved the sound of the unit as it was originally. I have considered going back to the OEM unit but I do really love the other features that I have now (nav, ipod, usb, backup cam, etc).

If you got a touch screen unit to successfully connect to the sound system, which one are you using if I might ask or how did you do it? I went through the thread here but I am not quite clear on what exactly you meant (and please excuse my lack of knowledge about all this). I was told by three different audio shops that looked at the car that it was basically impossible to get the Harman Kardon system to work with any after market touchscreen systems, so when I saw your thread I got a bit excited

thinush

Many of the 'chinese' android displays you can buy have the option to connect to optical out.
The big brands tend to not have that option (Like kenwood). This might be why they said it's not possible.

Look I still have to do this job. But one of my first steps would be to connect to the amp.
When I have done this I will give you my findings. But sadly, it's still a little time off :-) This car has been eating my finances dry, the moment I can... I will :-)

Adarah

Haha no worries, I totally feel you on that one!

I was just very curious when I saw this thread. & I didn't know that about those android displays from china. I might check into that. I find it strange that the big brands don't have the option - if the ones from China do its obviously something they could do as well.

Thanks for letting us know about your project though, and good luck!

thinush

I think its a compatibility thing.

When I looked around trying to find a similar amplifier with the same features like DTS I dont recall finding anything. People like Stereo. I can also imagine the amount of money thrown around to put in a new amplifier for someone that wants to buy a new head unit.

Also, all the big company head units sucks *****. They are really weak and playing catch up the whole time.

ralphedel

There is way too much technical information here for me but I need some information to help me make a decision of what kind of low-tech audio/gps system to replace the H-K system in my 2005 CLK55 AMG H-K system.

If I understand things correctly in my simplistic way, a fiber optic (FO) cable connects the dash head unit with the amplifier in the trunk. I assume it carries the signals for the speakers.

If a new dash head unit did not have a fiber optic output that would work with the existing FO cable, why couldn't good old speaker wires be run from the head unit through the car and tie into the existing speaker wires which I assume connect at the existing amplifier?

I do not intend to replace the existing amplifier at this time, although I might do that in the future. Making the speaker connections from the new head unit in the trunk at the existing amplifier seems to be easier to do than to run wires from the new head unit directly to each speaker.

I would appreciate any feedback on my comments, pointing out any errors on my part. Many thanks.

megacrazy

The connection between the head unit and the amp is fiber. The connections between the amp and the speakers are regular wire.

You can:

- replace the amp/tap speaker wires where the old amp was/run signal wires to the head unit from the new amp
- tap wires in the trunk where the old amp was and run directly off the new head unit
- find a MOST adapter and retain everything in place (2-300$)

Rudeney

You are correct.

That is exactly what you need to do in order to install an aftermarket system.

That's definitely the way to this and what I always recommend for this type of install. Just understand that this will bypass the factory HK (or Bose, for older models) amp. The amp is fiver in, speaker-level out. So you'll need amplification for the speakers. Of course most aftermarket head units do provide some small amplification that might be adequate for your needs. I would run coax RCA cables from the dash to the trunk. If you want to use your new HU's built-in amp, then just get adapters so you can use the RCA cables for speaker level wiring. Once you are ready to upgrade to a component amp, you'll have the connections ready to go.

tw2

I just replaced the head unit in the e-class with harmon kardon. I used the MOST adapter, worked perfectly. Just has a couple of limitations which didn't worry me. This is not too difficult and you can use any head unit you like.

If you decide to run the speakers from the new head unit, make sure it supports 2 ohms speakers (regular speakers are 4ohm). Same if you opt to use the factory speakers with an aftermarket amp but most good amps are fine at 2ohm anyway.

Link to my install if it helps https://mbworld.org/forums/w211-amg/...re-optics.html

Rudeney

Very nice write-up, TW2! One thing I noticed is that the MOST amp interface you used on;y support two channels, so you can't control fade. I also assume it loses the LOGIC7 sound processing - I know that is a function of the amp, but with only two channels out, I don't see how it would work. Also, are the HK speakers 2ohm? I know the old Bose speakers were, but I thought the HK's were 4ohm?

tw2

Thank you. Yes you lose the fade and surround sound effect. I am very happy with the fixed front rear balance it provides. I thought they were 2 ohm but I may be wrong. A relatively cheap and simple solution for those of us who are not too fussy.