OK,
I'm getting hooked on this computor-car integration stuff. While I'm pulling of faceplates, poking wires etc to try to hook my steering wheel remote directly to my riocar I want to attempt to do the same with my Onstar. The first piece of advise I need...... is it possible. Let me give the facts as I know them:

When onstar is activated it sends a signal via a class II serial data circuit to the headunit (thru a single wire) to mute the headunit. The voice is then played thru the amplifier. I can easily wire the incoming sound to the riocar aux. inputs. What I'd like opinions on: Is there a possibility to wire a class II serial circuit (single wire) to the riocar's serial input and find the signal used to mute the audio.

(yes there are convertor boxes I can but which I can hook up to the mute and use mlord's new hack but I'm addicted)

There is a special 'cellphone mute' input wire on the RioCar docking sled wiring harness.

Read your RioCar manual to identify the correct wire (and its colour) and check that the signal output from the Onstar interface is either +12V when external circuit is 'on' and 0V when its not,
or
its 0v when its on, and +12V when its not.

Assuming the voltage is no more than +12V [and if its less it may still work - but you'd have to try it to find out],
then connect your Onstar signal wire to the Cellphone Mute input and with some luck, when the button codes screen in Hijack is active you should be able to see the 'fake' button code being generated by the kernel whenever your onstar system is in use and when its not.

Once you have the codes, then its a simple IR map to do whatever it is thats required
[pause the player, switch to Aux input, unpause the Aux input source etc].

[and when the phone is finished with, switch to player, and unpause].

Hope this helps.

Thanks number6. I'll try that.

Bob

Do you know if all signal wires take +12V? I was in particular wondering about the headlight signal.

Hopefully the shop manual (diagnostics section) will tell me the voltage. Yang, could you elaborate on what headlight signal your referring to. I'd be glad to look it up or try to put a voltmeter on it if I knew which one.

I believe he's speaking of the Orange cable on the empeg sled. Or the ACC as it's referred to by Pioneer.

Well I believe the 'Headlights' in use signal wire is what you're talking about.

Its used to tell the RioCar/Empeg to dim the display to the (preset) display brightness value previously selected.

Don't quote me on this, but I would be very surprised if the Headlight on signal wire and the Cellphone Mute signal wire are not using the same RS232 Transceiver chip inside the player (just different pins on the transceiver chip) to convert the incoming higher voltage (ie. the 0 to 12v+ signals to the lower 3.3v signals actually read and handled within the hardware in the Empeg.

If this is the case, then the Transceiver should handle over 12 volts - but how much more I wouldn't care to say [maybe up to 24V but I wouldn't like to test it to find out - could be expensive to get fixed if it didn't].

Thanks, I thought he was talking about the vehicle. (duh)Of course he's talking about the riocar. The dimmer circuit I'm pretty sure is +12v (99.9% sure). It works fine with my truck's dimmer circuit which is 12v.

The headlights on/in use signal wire is usually wired [in the vehicle] to the dashboard lights that light up when the headlights are on rather than wired to the headlights proper (if you catch my meaning).

This is mostly for the reason that the wiring is right there - well within 2 feet of the din slots where the tuner/headunits go - simply connect to the wires that light the dashboard up and theres your "headlights on" signal wire.

Unfortunately, in my truck there isn't easy access to the dash light wires.. I'll have to look again though.. For my Fog Light control, I actually ran a line off of the headlights to a relay to act as a master switch.. I'm thinking, if I can find a good source for the signal inside the dash, that it would work a bit better.

Yang, did you check to see if there is a headlight/dimmer wire that ran to your original headunit. Most stock hu's have such a wire to adjust the stereo with the dash lights.

Number6, I don't really understand serial circuits. Is it that a serial circuit remains hot all the time but sends signals via voltage or code to various devices or is it that the signal sent causes a serial circuit to become hot. If it is the second then if there are other devices using the circuit other than onstar won't this "confuse" the mute line of the riocar. I hope I asked this clearly enough.

The Isuzu Rodeo (which I have) has no signals in the factory stereo wires. 4 +/- speaker wires, +12VDC battery, +12VDC ignition, and ground. that's it..

With classic Serial circuits( like a serial port on a Pc and/or a modem etc) there are a bunch of control signals (up to 4 in and 5 out from memory) - which could be either on or off (i.e. 12 volts, or 0 volts) that were used for the sorts of complicated processing back in the days when we had dial telephones and the like, plus there are 1 or 2 'data' signal wires, which are where the data being communicated goes, in a on/off (serial) fashion at a certain frequency [baud rate] and in a specific format [parity, stop bits, # of bits, 5, 6 7 8 etc].


The headlight on/off and Cellphone mute inputs to the Empeg are treated as if they are Serial control signals (even though they are technically nothing to do with serial communications).

For historical reasons the devices that convert the 12 volts or more on/off to 'control signal on'/ 'control signal off' is called a RS232 Transceiver and they are generally pretty toughly designed to take all kinds of electrical conditions that would fry the average chip - which is why they are used to convert the voltages present in your cars electrical circuits for lights and cellphone mutes etc to to much lower voltages used inside the RioCars.

gotcha...thanx

So the ir translations will map it with a unique requirement which other devices on the serial line will not "set off". Am I getting it?

since you guys are talking about onstar can i hook up my fosgate amps to my stock deck with onstar most instalers are scared to do it.

I just read you original post again and theres something to be aware of.

while there is a single wire going to your headunit, it could be a simple on/off signal, or it could be a serial data signal.
The first is easy - its either on or off (0 or 12v etc as discussed).

If the wire sends a stream of pulses rather than changes to a on or off state, then you have a serial interface and that gets really really tricky.

I don't know anything much about onstar - heard about it years ago when it was first proposed and thats about it.

You should measure the signal with a digital multi-meter set to the DC volts measurement with the range of maximum of 20 volts or so. [connect the black lead to your cars ground./earth - i.e. a metal part of the car, and connect the red lead to your wire.

Read the voltage - is it 0, or 5 volts, or 12 volts?

Then test your onstar system - does the 'signal' on the head unit wire change state [voltage] and does it stay that way until you're finished with the call?

If so, provided the voltage is not much more than 12 volts [and probably more than about 3 volts] when its in a call then I think its a wire that the Mute input on the RioCar.

If it briefly changes voltage only, then thats a serial data stream of some sort and thats more complicated by a long chalk.

Yes, we could make a device that will 'decode' the signal stream sent to mute [and unmute presumably] the headunit, then turn it into the mute on/off signal to the empeg, but that requires someone to stick a 'scope on the signals and work out the signal format, bit rate etc.
But you'd need to find someone closer to you than I am.

Thanks number6, that's what I was wondering. The shop manual refers to it as a serial data cable and I believe this to send a stream of pulses. I went back and read about the onstar convertors that are sold and they contain a microprocessor. I think I may need to buy one of these. The convertor contains a mute signal I can attach to the riocar mute line.

Oh well

If you are not planning on using onstar I don't think there is a real problem. Be aware, however, that some new amps have complex hookups that aid the headunit in controlling rearseat audio and maybe other functions. These functions might be lost with a new amp. What kind of vehicle do you have thrasher?

Again, not affiliated with this company, but this may be necessary for onstar to work...

http://store.clubgp.com/itemview.asp?itemid=60

I want OnStar in my car :<

Yes you're right, when you're dealing with this of kit you're best to pay the extra $$ and get the professional convertor.

However, in the meantime, you can still go ahead with the Mute input to Empeg stuff - I'd attach a small on/off switch between your cars (empegs) +12v source and the cellphone mute - that way you can 'simulate' a incoming call simply by flipping the switch on - that lets you get the empeg side sorted - which will take a little doing, and then when your convertor arrives you can then wire it in, instead of the switch.

But until the convertor arrives you'd only have to flip the switch to be able to tell the empeg to switch to Cell phone mode, and when its unflipped, the empeg would be able to resume normal programming as it were.

You may decide that thats enough to be going on with and not bother with the convertor at all [or at least postpone it until you want it].

Does the Onstar system trigger the cellphone mute on outgoing calls too or only on incoming?

Sounds like the ideal solution, the built in isolation and switching relay would not be used in a empeg installation using its Aux input - but you'd have to get the OnStar audio 'out' signals to the empegs aux in connectors as well.

Does the Onstar system trigger the cellphone mute on outgoing calls too or only on incoming?

Outgoing and incoming calls. Hmmmm......$110 for for starmod2.....$200 for handheld scope at radio shack

Don't forget to add your time to work out the data bit format and then programming up a micro processor to do the mute function etc.

For now I'd go with a manual switch and get that bit working
[at least its something you can use], then go from there.

Personally, if you feel comfortable with hacking the OnStar system and maybe blowing it up and your head unit etc - then go for it.
If you want a simple interface with a simple installation then the 3rd party add-on kit sounds ok.

Plus, I'm sure you could find a cheaper piece of kit if you looked around on the net a bit - but you'd still be paying at least $70 or so I think..

Its your decision.

When you put it like that. Actually there is an alternative which PAC will release in the next few months. I'll probably buy that. It interfaces directly with my PAC BOSE adaptor.
Thanks for all the discussion number6. I'm slow but I'm interested in learning!

I have a 2002 chevy hd truck

The microprocessor in this case is known as "the Empeg's CPU".

If you dig around in the kernel in empeg_power.c (I think), you'll find the mute code, with some Hijack hooks attached. If you were to keep track of mute samples over time, you could capture and decode the incoming bitstream.. with a bit of luck.

Or just blow the dough and save some time.

yeah, I'm not familiar with the 2002 trucks. If you do want to switch amps you can use an Onstar adaptor as discussed in this thread. (Soundgate has one and PAC will have one soon). These small boxes have a built in amp. The PAC will plu directly into your Onstar wiring harness. I think the Soundgate will require cutting/adapting to connect.

I may just give it a try (with my $200 Riocar).

A little correction: RS-232C (and V.24, IIRC) standards use +/- 12V, not +12V and 0V. -12V is called 'mark' and is logical true (or data '1'), +12V is 'space'. Idle data line is on 'space', that is, +12V relative to signal ground. However, there are many other stadard and proprietary serial protocols with different signal levels, polarity etc (e.g. empeg tuner port, which uses inverted TTL levels), so this tells us nothing about OnStar or some other proprietary solution.

Of course, I hope that memory still serves and I didn't mix up something