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Carputer - How to make your Laptop start up / boot automatically (video)

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  • Carputer - How to make your Laptop start up / boot automatically (video)

    I'm using a laptop in my carputer project, and needed a way to boot automatically when the car turns on (i.e. simulate a power button press when the laptop gets "plugged in").

    Laptops generally don't have the "Restore from AC power loss" BIOS setting, so I've used a simple circuit with a PIC microcontroller instead. I made a workaround and posted a video of my solution:

    Simple circuit with 3 components. Schematic is in the video (1:05).

    It's an IBM T60 Thinkpad connected to a docking station. The docking station has a tactile button to which I could solder the circuit (too messy to connect directly to the laptop, IMO). The power button is actually part of a 1" x 1" removable module, which made soldering very easy.

    There is a 5 volt signal tied to an LED on the docking station which is only present when the AC is connected. I'm using this to power the PIC microcontroller. When the PIC boots, a small program executes;

    In normal use, the power button works by shorting to ground. This program emulates a button press by shorting the power button to ground for 1 second.

  • #2
    This is the PIC code to use: (you can use a PICkit 3 to program the chip from your PC)
    // Laptop Auto Power on
    // Michael Vogel
    // (c) June 2013
    // This code is yours to use for your (non-profit) project

    #include "htc.h"
    #include "pic12f1822.h"


    /* PIC Configuration Bit:
    ** INTIO - Using Internal RC No Clock
    ** WDTDIS - Wacthdog Timer Disable
    ** PWRTEN - Power Up Timer Enable
    ** MCLREN - Master Clear Enable
    ** UNPROTECT - Code Un-Protect
    ** UNPROTECT - Data EEPROM Read Un-Protect
    ** BORDIS - Borwn Out Detect Disable
    ** IESODIS - Internal External Switch Over Mode Disable
    ** FCMDIS - Monitor Clock Fail Safe Disable

    // Using Internal Clock of 8 Mhz
    //#define FOSC 8000000L

    #define _XTAL_FREQ 16000000 // Used in __delay_ms() functions

    void init (void)
    OSCCON = 0b01111010; // set internal osc to 16MHz

    PORTA = 0x00; //Clear PortA port
    TRISA = 0b000000; // set port a bits to output (0) or input (1)


    void delay_ms(unsigned int milliseconds)
    while(milliseconds > 0)



    //Program is running (received power from AC adapter / 5 VDC)

    RA5 = 1; // "Pull-up" output pin
    delay_ms(1000); // delay i ms

    RA5 = 0; // Send output pin to Ground (imitate power switch)
    delay_ms(1000); // delay i ms

    RA5 = 1; // "Pull-up" output pin





    • #3
      This feature is already built into the Carnetix & Opus laptop power supplies but I guess if you were using an invertor to power your laptop, it would come in handy.
      My 2007 Ford F350 Work Log located HERE


      • #4
        Thanks for sharing! I am sure this will help a few peeps out that still run with inverter or even a DC laptop adapter. Maybe you could offer a pre-programmed solution for those without a pic programmer. Just a thought, Keep up the great work! SNO


        • #5
          I'm not too familiar with the Carnetix & Opus laptop power supplies - how is it interfacing with the laptop to automate startup?

          I decided to stay with the inverter route just to keep the project within a small budget - it works well now that I have all the kinks rolled out.

          If anyone thinks this circuit might be of use to them, send me a message here or on youtube & I can probably program a PIC for you to use.


          • #6
            Both those power supplies do require a connection to the power button of the laptop and are somewhat expensive but they are loaded with useful features. They offer a start-up & shutdown controller, they withstand voltage issues while the engine is cranking plus they have a 12v clean output for monitor etc and available 5V output for USB hubs etc. They also offer a delayed 12v output that can be used to trigger amps to eliminate turn on "thump". You can see how I wired my laptop & a detailed pic of the Carnetix P/S on Post #7&8 on page 1 of my work log (link below).

            You solution for anyone running a power invertor will be very handy! Thanks for sharing this with everyone.
            My 2007 Ford F350 Work Log located HERE


            • #7
              For laptop users, the suggestion of using a docking station for this very purpose has been suggested for years.
              The Carnetix PSUs will do the same thing, as someone mentioned above.
              They will trigger the power switch when the car's ignition is turned on. Looks like your little hack performs the same function as the startup controller built into the Carnetix units.
              Probably cheaper, too.

              Kiddies, we're talking about a TRUE docking station, not a cheap piece of crap USB expansion dock that gives you LPT, COM and extra USB ports.
              A USB expansion dock (or whatever it's called) WILL NOT WORK FOR THIS PURPOSE.

              Most "consumer spec" laptops don't have a docking station option. That means the one you bought as a great deal form Best Buy on Black Friday probably doesn't have provision for a docking station.
              Have you looked in the FAQ yet?
              How about the Wiki?

              Under normal circumstances, a signature would go here.