Re: User request

[bruzas]

Hi,

I don't know if this is the right place to ask or should I create a new thread, correct me if i'm wrong.

I've read though the forum and haven't noticed anything related - is it possible to implement reading music from a USB memory stick function? I can see, that steering wheel and IHU buttons can be used, so one button could be used to switch through BT and USB mode. I'm no good in softwares and codes etc., just soldering and analog circuits, so no idea if this question is something from sci-fi.

[Seth]

BlueSaab is simply a bluetooth gateway to the Saab audio system. This module isn't designed to play music from a usb drive. The easiest way to do that would be to find some sort of device that would interface usb and let you send it via bluetooth to the rn52.

Something like this would probably work
http://www.ebay.com/itm/Bluetooth-Car-Kit-MP3-Player-FM-Transmitter-Wireless-Radio-Adapter-USB-Charger-/361353056050

on second thought, that device might not let you stream the usb audio TO bluetooth, which is what you want...this device send audio via FM transmitter, which sounds like garbage.

I'm sure such a device exists...usb mp3 to bluetooth...

[bruzas]

As I understand, the bluetooth module receives "something" from the phone, then processes it and outputs "something2" to the CDC line going to the IHU. What I was thinking - maybe somehow interrupt that "something2" (for the sake of the argument - just cut power to the BT module), and feed that "something2" from USB, aux etc.

Of course to receive "something2" from a USB stick would require data processing with additional hardware, but hey You guys hacked in to the CAN line and can feed the whole system with what you want the system to see, whats some data processing compared to that... :)) And as you already mentioned - 100% that such thing exists pre-made, one just needs to know what to look for.

What is the "something2", that the module is feeding to the IHU? I don't believe it's an ordinary high or low analogue signal, nor the balanced one, that SAAB uses to send audio from IHU to the amplifier.

[Seth]

There are 2 things going on; 1) the canbus lines talk to the car and tell it to 2) turn on the CDC audio lines.

You can connect whatever you want to the audio lines and play whatever you want once the audio lines are turned on. The car uses balanced audio wires, hence 2 for each channel. You'll probably need an unbalanced-to-balanced adapter to convert from a standard 3.5mm plug to the 4 audio lines.

[bruzas]

So if I build the BlueSaab module, connect it to the car all I would need to do is cut in to pins 40, 41, 42, 43 on RN52 and feed balanced audio signal, to get it to play on the car stereo?I do understand the controls would no longer work, etc.

I guess what I'm trying to get out of this is a Yatour analog suitable for SAAB's

[Karlis]

I'd say that in this case it would be even easier for you to build a 3.5mm module and use it's L/R in to hook up some USB player.

[bruzas]

But in the end it's back to the basics and good old TELEPHONE aux-in method, Karlis. What would be awesome is BlueSaab with the capability of playing from any source - be it BT or USB stick or a memory card - with already implemented controls from IHU ant the steering wheel and also with information on SID. I thought maybe there is an easy solution, but nobody thought of putting it there in the first place...

[Karlis]

TELEPHONE aux-in mod, of course, works. But it just gives you L/R channel audio. No control over CAN bus, so no steering wheel button handling.

I would assume that BlueSaab could be modified to play back audio from an USB stick or SD card, but given its location one would have to keep it either visible in the trunk, or run a wire from dashboard (where USB/SD reader is connected and integrated) to the trunk.

[bruzas]

Given that i found such a compact (and cheap!) solution from china (Aliexpress) it might even be possible to fit everything in one box. Or that could be another dongle for whoever wants it.

Or f.e. this project. From what i found it would cost ~10€ in parts + the PCB + data "extractor" from USB. And, of course, software production. I can't comment on the coding part, because I've no experience, but from what i can see the device decodes any format of mp3 data and converts it to analog L/R output AND it can be controlled through some I2C protocol (hard/easy?).

So an additional 7-8 pin connector, maybe a dongle/maybe a small PCB in the same box with some cheap hardware, software for selecting input source and controlling the new parts, and....?

Also, I've been looking at the RN52 datasheet - I don't believe it outputs balanced audio signal to the IHU. They use something called "differential signals" and I'm not sure those two are the same. Extract from Wiki says it can run on single end signals, if done right. If I'm right that makes thing a bit easier, because of more existing decoding and converting solutions. Or an adapter can always be built, but it costs money.

As for the "visible in the trunk" part - I, personally, can't see any problem about sticking a 64GB USB stick, full of music, and throwing the whole thing behind some panels (or, as I drive a wagon, most probably in the side compartment). I don't imagine I could listen through all the music in a year :D