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Cheap way to PC read 12v signals?

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  • Cheap way to PC read 12v signals?

    Hello all,

    Is there any cheap way to the carpc read 12v signals from the car?

    What I want to do is make carpc aware of 4 or 6 signals in the car, like doors open, 4x4 mode, headlights one, etc. is there any cheap way?

    I was thinking in using a serial to usb adapter, but how wire the serial to the 12v peripherals? And how about the software ?

    Thanks for any help!

  • #2
    Have a look at arduino's. Pretty cheap mictrocontrollers that you can program to read digital signals. That's what im using but atm its not complete.

    More google searches will reveal alot more and its pretty easy to learn.


    • #3
      I believe there are even optoisolation shields for the arduino, so you can plug 12v signals right in.
      "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
      My Shop


      • #4
        Rather than serial - maybe a USB to (bidirectional) parallel interface.
        That'll take at least 8 inputs, plus the handshakers (another 2-4 lines?).
        Else use the 8 data to encode 63 inputs....

        I've seen para2USB for $10 upwards, but their RRP is usually ~$30-$70 hence making Arduino attractive.
        The Arduino Duemilanove has 6 analog & 14 digital I/O ports (and USB interface)...
        That's probably the way to go,


        • #5
          Bought one brain fusion to test (bought a semi defective one for us$ 20 + s&h). lets see what can they do.

          Thanks for the info!


          • #6
            there is also the usb io box from mitch with 4 input and 4 relays
            Blessed are the "cracked" for it is they who let in the light.


            • #7
              well, let me see


              • #8
                having the arduino and the mjs-io's. arduino's are amazing but harder to set up and integrate. mitch's device is uber simple and work so well with RR.
                New System in progress:
                Phaze TD1500 ~> Dynaudio MD130
                Phaze TD1500 ~> Seas g18rnx/p
                Zapco Ref 500.1 ~ 12" tc-9
                Behringer DCX2496 ~ Envision Electronics psu
                Transflective Xenarc

                My Car Pc Install
                My Boat Pc worklog


                • #9
                  First, you need to be sure that if you can see these through can network then you can just program a microcontroller or buy a canbus reader then you dont have to wire almost anything.


                  • #10
                    Depending on how the signal works, there are different ways to interface this. One of the easiest ways is if the signal is 12V when inactive and grounded when active. Then all you need to read it is a diode. You point the cathode of the diode towards the 12V which will prevent the 12V from entering the arduino. Pull up the line on the arduino side.

                    When the signal is grounded, current will flow through the diode (the arduino 5V pulled up) and you will get a LOW. When 12V is present, no current flows and the pullup makes the arduino pin high
                    Pullup Resistor to 5V
                    12V -------|<----|-----Arduino Pin


                    • #11
                      Depends on what you call cheap. I bought the Phidget 1012_2 Digital IO to interface with Driveline. It has 16 digital inputs and 16 Open Collector Digital Outputs to directly control substantial devices, switching up to 30VDC at up to 2 Amps. $100 bones is cheap.


                      • #12
                        You can also use simple microcontroller. I am using mcp2025, I got it from a local shop for 1.5usd. And It makes things quite easier. You can even connect and serial bluetooth device to it communicate with the car over bluetooth.