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Thread: Opus and the ignition switch...

  1. #1
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    Opus and the ignition switch...

    Alright, to start, I've been a member for a while, lurking like crazy to try to read and learn as much as possible about this before even attempting to start a project. In that time, I lost my Monte LS to a drunk driver (I walked away from the accident, thankfully) and have acquired a 1998 Lumina LTZ. I still had some of my CarPC stuff laying around (10 gauge wire, a fuse-holder, and a few other small, negligable items.) So I'm now getting back into the swing of things and planning on getting this CarPC in by the end of August (Realistically, it'll probably be August '07. )

    Now, let me get on to my question. I've seen a thread in my searching on how to create a killswitch for the Opus power supply using a simple rocker-switch. That I kind of figured out on my own on how to wire. But my question here is not about how to make that killswitch. I want to know how to create a pushbutton that simulates the turn of the key to the ignition position. I'm looking for something similar to the pushbutton on the front of most ATX cases.

    If it has been discussed/found/done before, which I'm sure it has, and I just overlooked it somehow, just send me a link to the thread with it? If not, is it even possible, or am I just barking up the wrong tree, and should just tap into the ignition switch? I'm afraid to do that, however, because of GM's PassKeyII technology, and I'm not 100% sure how it works. I don't want to entirely disable my car because something isn't right according to the car's PCM because of PassKeyII.
    "So... wake up, Mr. Freeman, wake up and... smell the ashes." ~G-Man: Half Life 2

  2. #2
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    I don't know specifically about the Opus but the M2ATX has a jumper for connecting a cases power button, you could easily just run really long wires from this jumper to a power button installed in the dash.

    taping into the ignition isn't as scary as you may think, unless you have every option available for your car there are probably many wires running under your dash that go to nothing at all, some of them well be constant power and others well be switched with the ignition, you just need to get a simple power tester and spend some time upside down in your car looking for them. In my sunfire it seems the yellow wires are ignition switched and the red ones are constant power.

  3. #3
    Variable Bitrate Freelander's Avatar
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    ravant,

    you need to conect 12volts +/- at any time to your opus ignition input, to trigger it to turn on. the best place to get guaranteed power like this is directly from the battery (or an always powered distribution block). run a small wire, since the opus won't draw much, from the positive terminal to the opus ignition, and intall a small (non-momentary) on/off switch to break the line.

    the opus would only turn on when the switch is open, always trun off when the switch is closed.

    things to think about:
    1) every time you want to turn your computer on, you need to press the switch.
    2) if you forget to press the switch off, the computer will stay on and drain your battery.

  4. #4
    Newbie Erazor983's Avatar
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    Most automotive starter circuits draw upwards of a hundred amps when you turn the key. Adding another ten to twenty amp draw from your carPC booting at the same time may seem trivial, but it isn't.

    Automotive batteries have a bad rep of being labled at twelve volts and too many people think they never deviate from that voltage. Problem is a cold crank can drop a battery as low as ten or eleven volts, and when the engine is running the charge circuit can be recharging the battery at as much as fourteen volts.

    While the overvoltage isn't much of a problem for your carPCs DC/DC power supply the undervoltage is. If you setup your PSU to boot your carPC at the same time as the engine cranks the ten volts may not be enough to boot on and your carPC simply will not boot.

    A better method is to use a relay trigger off the 'ignition hot' circuit to trigger a timer of five to ten seconds so that your PSU will boot your system after your engine is running. If you need some help with a timer circuit drop me a PM and I'll help you setup one.

  5. #5
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    I was actually trying to get around the whole relay alltogether and just create a soft-off button in my dash, this way the PC's off, I start my car, then press a button, and let that be that.

    I've got an LTZ of the Lumina, and this thing has everything except OnStar. There are a lot of wires that are used, especially for the security system. For PassKeyII, there is a resistor in the key that tells the car's computer, "This is the right key, let it start." or "This is the wrong, or no key, don't start." I don't know if PassKeyII uses a seperate wire going to a sepearate location, or if the resistor accepts the starter switch's voltage, drops it on its own, and that specific voltage level is read by the system. If I find more out about PassKeyII, I'll consider tapping into the ignition and putting a 5 second relay in.

    My biggest question is, Freelander, you said you need to connect a 12v +/- to the Opus ignition switch to get it to turn on. How does that work? Is it a momentary contact, one pulse of 12v gets it to turn on, a second turns it off (and a 6 second hold is a hard-off, like ATX PSU's)? Or is it, switch holds the 12v closed, and while it's closed, the Opus is on, and if the swtich opens the 12v, the Opus goes into a soft-off?

    And I'm not worried about forgetting to power down the PC, because I'm going to have a locking cover for my in-dash screen. I already fabricated a quick prototype of my switching mechanism with the lock. As you swing the lock to the unlock or lock positions, it comes in contact with a switch. That contact will be what I want to trigger the on/off of the Opus machine. So the general procedure for my startup will be as follows:

    Get in, close door, buckle up, start car, deactivate killswitch, unlock and open screen-cover. Done. Now the computer will be resuming from hibernate.

    From that, my shut-down process will be similar.

    Put car in park, set parking brake, close and lock the screen cover, shut off car, wait for soft-off confirmation LED, hit the killswitch, unbuckle, open door, leave, close door, lock car.

    The other thing is, I have an AUX input for my CD player, so I'm going to be running the CarPC audio through the radio first, so this way, if I have a really short trip, but still want music, I can do it the old-fashioned way and pop in a CD, or tune to a local station. So the on/off status of the PC really doesn't matter. It's an extra for some of my really long trips, say my commute to work and back, or for the yearly roadtrips I make.
    "So... wake up, Mr. Freeman, wake up and... smell the ashes." ~G-Man: Half Life 2

  6. #6
    Variable Bitrate Freelander's Avatar
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    ravant,

    i was mistaken before. i though you wanted to start the computer without the inserting the key. what you actually want to do, is turn the computer on and off with the key staying in. this means that the key must be in, AND the switch must be "open" for the computer to start.

    here is the link to the FAQ section on "How to Wire an OPUS PSU".
    what you want to do is actually pretty simple. just install a switch to break the yellow wire that runs from the ignition wire to the opus input.

    the opus does not have a pulse start, a feature standard on my carnetix.
    therefore, the switch you use cannot be momentary. it must be toggle between open or closed. if you really want a push button, this might work. push it to turn on, push it again to turn off.

  7. #7
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    I did read that FAQ. Seeing as the switch indeed has to be a standard full-contact rocker, how would I wire that? Because - the FAQ is setup as such to show how to wire it to the ignition, rather than where I'm going with it. Do I just run a wire from the + on the PSU switch wire, then to the switch, then to the - on the PSU switch? Or does there have to be some kind of external power source involved?

    I apologize for asking so many questions, but at this point, I'm fairly sure about everything except the Opus switch. Once I get a camera and/or a scanner, I'll post my plans and already-constructed pieces online.

    PS: I'm kinda glad it's a rocker rather than a push-button, that's easier to throw using the locking mech than the pushbutton. And somewhat more reliable in the long run.
    "So... wake up, Mr. Freeman, wake up and... smell the ashes." ~G-Man: Half Life 2

  8. #8
    Variable Bitrate Freelander's Avatar
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    first, the red wire goes directly to the battery, while the black can go to the battery or frame. the yellow wire has nothing to do with either the red or black wire. the yellow wire goes from the ignition line, to the opus, with a switch installed in between. take a look.



    the on, or "open" position, is usually denoted by the white dot. when NOT pressed, the switch is "closed". this means current will not pass through the switch. (see the black contacts inside the switch.)
    when the rocker with the white button is pressed, the switch is on, or "open". then, current passes through the switch to the opus.

    i hope you like my ms paint skills, but this is going pretty far. soon i'm just going to come to your driveway and install it for you. where the hell is shirley?

  9. #9
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    Quote Originally Posted by Freelander
    first, the red wire goes directly to the battery, while the black can go to the battery or frame.
    I knew about that part. The switch circuit is isolated, which makes total sense to me. The yellow is for the switch, and goes to the ignition line as you say. However, the whole point is, I'm trying to eliminate the connection to the ignition line alltogether. PassKeyII utilizes the voltage, and any tiny change in it tells the car "This isn't the right key, don't start." I could be wrong about this, but I don't want to even try being wrong. I guess to re-word the question better, is there a constant-on line I can connect to somewhere, and just throw in an STSP between it and the sensor line? Perhaps an even better question is, what exact voltage needs to pass through the sense line to trigger the timer?

    So essentially, the whole circuit will be as follows, (My MS-Paint skills suck, bear with me...)




    Where Orange is some constant-on that is not the ignition, yellow is the switch, red is the +, and black is the ground. So, textually, the circuit for the power would be as follows:

    Battery -> Fuse -> DPST Switch -> Opus -> DPST switch -> Battery

    Then the sensor circuit would be as follows, (Again, textually),

    Constant-on line -> SPST Switch -> Opus

    Does this seem right? One switch for a hard-on/hard-off function for when the car is not in use for extended periods of time, and a switch for soft-on/soft-off functions as well.

    And while I do admire your MS paint skills, them being significantly better than mine (as I've clearly demonstrated, I suck.), I'm reasonably certain that the "On" position is considered "closed" in an electrical environment, while the "Off" position is considered "open" in the same environment. An open circuit is not completed, therefore power cannot flow, and a switch is off. A closed circuit is when the whole circuit is complete, power can flow, and the system is therefore on.

    BTW: Shirley is all the way in the middle of Suffolk County, exit 67, 68, and 69 on the LIE.

    Quick Edit: The red box in the MSPaint drawing is the fuse/fuse holder. Only the word "Fuse" made it in.
    "So... wake up, Mr. Freeman, wake up and... smell the ashes." ~G-Man: Half Life 2

  10. #10
    Variable Bitrate Freelander's Avatar
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    4 posts and i guess i still don't understand your question.

    first, i am in no way familiar with "passkeyII". if i understand correctly, you don't know the voltage coming out of the ignition line, therefore are insure that this will trigger the opus. use a voltmeter and measure the voltage coming from the ignition line in different situations. i believe that the opus ignition switch takes roughly 12 volts. i haven't checked it.

    if you want to put a switch in the power feed line, use a high amperage circuit breaker.

    also, don't put a switch in the ground line. that's just going to lead to problems.

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