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CarPC wake on AC plug

Discussion in 'General Electronics Discussion' started by nynex, Apr 15, 2012.

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  1. nynex

    nynex

    4
    0
    Apr 15, 2012
    Hi everyone, I have been working on installing a CarPC and I am using a laptop for the main computer with a touch screen etc. I have had trouble with waking the laptop from sleep when the charger is plugged back in and it's no longer on the batteries which after some reading seems to be a limitation of the BIOS with laptops.
    Now as a workaround I was hoping to use a USB mouse circuit board ( all the drivers are there to wake the laptop up with that ) but I need to simulate the button press when the cars ACC is switched. any ideas what I would need to use to do this or what I can start to search for?
    My guess was a relay of sorts but it only needs to be like a pulse or something to complete the circuit and not be on all the time that the ignition is on.
    I have a friend who helps me a lot with electronic stuff but he's a bit busy lately so I thought I would try to find what I need here.
    Thanks in advance
     
  2. selanac

    selanac

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    Apr 15, 2012
    Couldn't you go into the Bio's and turn the Wake on AC off? Just use the screen saver, and turn your computer off when going from the car to where ever you're going into, House, Work, Hot Spot, etc.
     
  3. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    This could be as simple as a hacked mouse or keyboard that sends a movement or keystroke upon power up to a proprietary circuit that simulates a keyboard/mouse and send the fake movement to wake it up...

    A lot will depend on your skills and/or your budget...
     
  4. jackorocko

    jackorocko

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    Apr 4, 2010
    a hacked keyboard it is. But are you willing to tear apart and modify a laptop that is under warranty?

    could you simulate a mouse movement with a wireless usb mouse? Hack the interface and send it a fake pulse, you pay twenty bucks for the mini mouse and usb receiver. Hack the transmitter to send upon ACC switch on.
     
    Last edited: Apr 18, 2012
  5. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Any current laptop should have support for USB keyboards, so there is no need to tamper with the laptop itself, you can hack a $10 usb keyboard and get the job done same as a usb mouse...
     
  6. nynex

    nynex

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    Apr 15, 2012
    I can't just use the screensaver because of power consumption is too high.
    The laptop isn't covered by warranty and I am an IT tech for a second user IT company so we have spare parts etc for me to work with for both the laptop and mice etc. so thats not a problem.
    I would like it to send a fake pulse or movement but how would I go about having it make the fake movement?
    It needs to just be a momentary current I'm guessing but where would I begin to look for a circuit to build for it?
     
  7. timothy48342

    timothy48342

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    Nov 28, 2011
    Your saying, "Where on the mouse?" I would think the left mouse button.

    If I understand right, you already have the laptop set up to wake-on-left-mouse-click using a USB mouse, and your willing to sacrafice the mouse?

    Open up a mouse and each mouse button has a little microswitch connected directly to the circuit board. Short that switch briefly and the comp comes on.

    Am I missing something?

    -tim
     
  8. nynex

    nynex

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    Apr 15, 2012
    The mouse is apart and yes that bit I understand, the part I am stuck with is how to make a device that knows when the Car Ignition comes on and then makes that fake press?
    I know it can be from the cars ignition controlled 12v to detect the car on part but when then do I use to make the pulse to fake the press of the mouse button?
     
  9. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    What I was thinking is why would anyone want to hide a keyboard in their car, but I guess if you hacked it up into the internals, it would be plenty small enough. There is a youtube video on hacking up a keyboard into the good parts and shows you how to simulate key presses.

    I still like the idea of a wireless usb though(keyboard or mouse). No need to ever remove wires if for say the laptop needs come out.
     
  10. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    All you need to do is short the leads together of a key. see here A key press is recognized when the circuit to that key is closed, think two metal pads, when you press the key, they connect. When you release, they disconnect. The keyboard controller will do the rest.

    I am thinking something like a RC network tied to a relay coil or similar. On power up the relay coil will engage shorting the leads for the simulated key press, then as the cap charges up the relay will drop out and you should be good to go.

    Notice this will not work again until power is removed and the capacitor drains.
     
    Last edited: Apr 18, 2012
  11. timothy48342

    timothy48342

    218
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    Nov 28, 2011
    Hey, jackorocko!! I started drawing this before your post, but here it is anyway.

    I was thinking with wireless you either have to change out the batteries or find a way to supply it with power from the car. With hard-wires usb, you have one more plug to disconnect each time you pull the comp out. But either would work.

    As far as the circuit... Whould this work?
    [​IMG]
    The size of the cap would depend on how much current needs to flow through the relay to make it turn on before the cap stops the flow. Maybe 100uF or so, I am guessing. Maybe a little more. Depens on the relay.

    The resistor would depend on the cap, of course. It could be excedingly large. Your not going to want to wake up your comp twice within 5 minutes or so, you just want the cap drained by the next time you do. It needs to be large enough that the relay can't be power through it. 250k-ish maybe??


    -Tim
     
  12. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    No, the resistor needs to be in series with the cap. As the cap is effectively a short when power is supplied the NEG side of the cap will see 12V, as the cap charges, the NEG side of the cap voltage will fall eventually close to ground. You will only need a short pulse, like a key press, which is a fraction of a second.

    Code:
    + --> cap --> | --> res --> -
                  |
                relay
    
     
    Last edited: Apr 18, 2012
  13. nynex

    nynex

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    0
    Apr 15, 2012
    Brilliant Thanks guys that looks like the sort of info I needed. I just need to knock it up and see how things go.
    The using a USB port etc wont be too much bother me too much because my intention is to put the laptop onto a docking station which would make it easier to remove it all.
     
    Last edited: Apr 18, 2012
  14. timothy48342

    timothy48342

    218
    1
    Nov 28, 2011
    (LOL. Were all posting back and forth at the same time.)

    Jack... are you sure. So when the cap drains, it drains through the realy and through the accessory connection??

    -t
     
  15. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    Yeah I am positive. Someone else can back me up if they want, but steve taught me this little trick a while back. I should add that relay may not be the best option here because of contact bounce, but maybe an optocoupler or something similar. I just mentioned relay, because most people know how they work so it is understandable.
     
    Last edited: Apr 18, 2012
  16. selanac

    selanac

    22
    0
    Apr 15, 2012
    I read somewhere that you add resistors to limit the voltage. Otherwise your LEDs will be real bright, and cause them to burn out faster or limit the life time of the LEDs.
     
  17. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    they limit the current. ;)
     
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