Saab mic

[Seth]

The mic pins in the Saab roof console should be as follows (from the WIS)
Pin 1 - High Level Output (active)
Pin 2 - Low Level Output (passive)
Pin 3 - Ground


These pins go to the 10 pin connector behind the passenger side center foot well kick panel
1 - +30 (constant power)
2 - +15 (ignition power)
3 - Ground, microphone
4 - Ground, mobile phone
5 - Telephone mute control
6 - Rheostat
7 - Telephone line output, signal
8 - Telephone line output, ground
9 - NC
10 - Microphone (low level output)

Some places in the WIS, they state to use pin 9 for certain phone models, pin 10 for others. I think it all depends on which pin the mic is connected to; you can switch the pins to either high or low level.

[Ziq]

Edit: I forgot to put in a big THANKS for sharing your project and inspiring me to take up my own! Really appreciate it!

Since you integrated a 3.5mm jack on your pcb I guess you have a pretty good idea how to connect this?

I just ordered a RN52 (although on a breakout board, going for a easier solding job..) and I guess there is need of an extra circuit to change from single pin to differential input?

What do you mean with "you can switch the pins to either high or low level"? As I understand it MIC_BIAS is used to pwer the microphone, and I guess we should go for active then? Or does that depend on which microphone that is installed in the car?

[Seth]

I haven't been able to use the saab mic yet with this design (rn52)...the audio doesn't come in very well, and I'm not sure why yet. It could be because I haven't played with the Mic_Bias line (in software), or because the mic needs more circuitry...? I have't been able to get it working, but Karlis is pretty confident it will work eventually :)

[aaronbguerrero]

I posted a comment a minute ago about this before I saw the forum :).

I've been using an RN52 for a couple years now with my Arduino setup (tied in the Saab CAN i-bus). I can't get the in car mic to work with it though. I've tried a few different circuits I've found online but nothing seems to work. The level is very low.

Please do post up if you figure it out, this is the missing link for me in terms of making this system 100% functional. (Well song title on the SID would be nice, but that's not essential for me).

Also, let me know if you'd like to look at my code or circuit diagrams, could be helpful!

[Karlis]

I'm not quite "captain hardware", but I believe the whole thing has to do something with how the original "Telephone" functionality was/is supposed to work. My guess is that the built-in mic goes through some "box" (preamp?) whenever the "Telephone" functionality is enabled - witchcraft happens - and everything works fine with mic-in signal being high enough for a normal sound quality on the other end. I don't believe that SAAB engineers in all their OCD-ishness would have designed such a POS. Unless this was the part that GM guys took care of... :)

Anyway, long story short - I believe it should work fine. Just have to figure out what the "original" mic connection goes through and how it works. Maybe we need to find some old wiring harness for some old "SAAB supported" phone (Nokia, Motorola) on eBay and use that for reverse engineering...

[aaronbguerrero]

I'm DEFINITELY not captain hardware :) however, I am an audio engineer by trade and I know a thing or two about mics and amps. 

What I can tell you is that at least in the 9-5 the mic runs directly to a harness behind the head unit, no electronics involved. Well, there are a few components inside the mic itself but I'm not sure of their function. (I had an extra saab mic to break into pieces and look at). I just pulled the circuit diagram from the workshop manual and confirmed its directly wired. 

Anywho, I've tried wiring the mic directly to the rn52 with poor results. 

I'm down to keep working on this with you guys if you want help, it's such an awesome project! 

Sent from my iPhone

On Dec 1, 2015, at 10:03 AM, Karlis [via BlueSaab Forum] <[hidden email]> wrote:

I'm not quite "captain hardware", but I believe the whole thing has to do something with how the original "Telephone" functionality was/is supposed to work. My guess is that the built-in mic goes through some "box" (preamp?) whenever the "Telephone" functionality is enabled - witchcraft happens - and everything works fine with mic-in signal being high enough for a normal sound quality on the other end. I don't believe that SAAB engineers in all their OCD-ishness would have designed such a POS. Unless this was the part that GM guys took care of... :)

Anyway, long story short - I believe it should work fine. Just have to figure out what the "original" mic connection goes through and how it works. Maybe we need to find some old wiring harness for some old "SAAB supported" phone (Nokia, Motorola) on eBay and use that for reverse engineering...

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[Seth]

my top console is still dangling wires, since I don't know which impedance we should be using...still more testing that needs to be done in order to try and figure out how to use this stupid mic. I think that we need to try playing with the MIC_BIAS line (via software) for one, and two, maybe see if we need any more circuitry (I saw something in the RN52 datasheet about the mic needing a high value resistor to ground on the mic line if the impedance doesn't match...?)

If neither of those work, then I'm at a complete loss how to get the Saab mic to work.

[aaronbguerrero]

Haha, you should see behind my dash with the wires, it's a mess!!

I haven't tried playing with the mic bias, I don't remember seeing a command for that on the rn52 datasheet, but I could be wrong.

I did find one site where an actual electronics person tried to get a different mic working, and she had her own problems. Her solution involved a circuit which I haven't tried yet. Here's the link: http://www.jenrathbun.com/Electronics/rn52-bluetooth-adapter-microphone/

On Tue, Dec 1, 2015 at 1:14 PM, se4587 [via BlueSaab Forum] <[hidden email]> wrote:

my top console is still dangling wires, since I don't know which impedance we should be using...still more testing that needs to be done in order to try and figure out how to use this stupid mic. I think that we need to try playing with the MIC_BIAS line (via software) for one, and two, maybe see if we need any more circuitry (I saw something in the RN52 datasheet about the mic needing a high value resistor to ground on the mic line if the impedance doesn't match...?)

If neither of those work, then I'm at a complete loss how to get the Saab mic to work.

'00 Viggen

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[Da Bear]

I have sourced a original mic from a junk 9-5 today  so I'm going to do some trial and error on my desk when I have the module.

[Nickhe]

Can you show me a picture how the it looks and the connector ? :)

[Da Bear]

This comes from a -00/01 9-5 so connectors may differ depending on year and market.

18 pin connector under dashboard.

EDIT: Added Pinouts
Counting from top left
1 : Common ground
2-3 : NC
4 : Phone mute control
5-6 : NC
7 : Phone line output ground
8 : NC
9: Microphone ground
----
Counting from bottom left
10 : +30, constant power
11 : +15, ignition power
12-13 : NC
14 : NC / *Microphone low output
15 : NC
16 : Phone line output
17 : NC
18 : Microphone output / *Microphone high output

*Possibly different wiring on certain markets (3 wires from microphone to connector), not sure.

Here is the microphone itself.
Looks like an electret mic. But that's out of my knowledge. Marked '55AF02'.




When I have some spare time to spend I will open up my current Sone Ericsson Bluetooth module to investigate the microphone magic that happens in there, since Saabs mic works great with it.

/Björn

[Ziq]

Looking forward to see what you find!

[Da Bear]

Found a second hand SE HCB 700 to play with. But it's a pita to reverse engineer, 3 or 4 layer board.

I might have gone the wrong way with this.   Time will tell.

[Da Bear]

Done some beeping today on my HCB 700.
Nothing really fancy from the mic plug to the bluetooth chip. Similar circuit as in the BlueSaab module.

But audio out from the bluetooth chip goes through an Amplifier - Texas Instrument LM4950TS.
LM4950 Boomer ™ Audio Power Amplifier Series 7.5W Mono-BTL or 3.1W Stereo Audio
Power Amplifier 
http://www.ti.com/lit/ds/symlink/lm4950.pdf

I can give it a try to draw a simplified schematic some day.

[Seth]

Thanks for looking into this...

so you're saying that the audio from the mic in the car, is amplified before being sent to the HCB 700? Or do you mean the audio from the HCB700 is amplified before being sent to the head unit...?

[Da Bear]

It's amplified before the IHU :)
Mic in -> Bluetooth -> Amplifier -> Audio out -> IHU.

[Da Bear]

So I was somewhat bored today and have tried my best to draw a schematic over the HCB-700 microphone magic.
Have yet to power it up and measure mic bias. Maybe tomorrow...  

I hope this is somewhat useful - and understandable. I suck att drawing schematics .

[Da Bear]

Powered up the SE beast on my desk and did some measuring today.

Mic BIAS is always active.
At high impendance BIAS is 1.74v wich works really good.
At low impendance BIAS is 1.9v and sound crap. Almost no sound at all.

I'm gonna update my schematic with some more measured voltages and minor corrections. Someone clever enough could probably calculate resistor values from this.

[Seth]

that's awesome man. if you make your schematic edits finalized, i can put them on a pcb :) so this schematic is what we'd need to use to take the mic output, amplify it, and then be able to use it for the rn52 mic inputs?

[woody_matt]

Whilst adding this functionality to the module, would it be possible to add a pre-amp with adjustable gain to the audio output so that the audio level experienced at the head unit is comparable to the radio or tape signals (i.e. remove the volume disparity). Would getting good sound quality from this be an issue?