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aldl interface without 12 volts.

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  • #16
    Originally posted by PPI Typhoon
    I just bought my parts for making a few cables last night. It's using the Maxim MAX232 chip. It also uses a 5V regulator to use power out of the serial port. I think if you don't use the regulator, it could be problematic. The schematics I'm using are here (actually Bill, I got this from one of your earlier posts):

    http://www.home.aone.net.au/techedge...e/8192schm.gif

    The MAX232 seems to be a pretty common IC used in active serial port interfaces. I should be assembling it this week. I'll post my results.

    Anyone know where to source a molded ALDL connector?? If not, I'm also thinking of permanently mounting the adapter in the truck with just a serial port in the glove box.

    BTW: Parts for 3 cables (minus the serial cable and project box) was $20.24 at a local shop. Pretty cheap.

    I didn't use the regulator, I don't think.. mine worked. There are versions
    of the MAX23x line that will accept higher voltage on VCC. I'll have to
    look at my old cable. I built it for a VB app I was writing years ago.

    That schematic looks pretty close to the same thing I have wired up.
    Pretty much the app note from MAXIM, with the power supply part added.

    One thing - gotta make sure the S/W you use is setting both those lines
    to +12. If it's only one, it likely won't have enough drive.


    Dig
    Dig
    11.94@114- 100% stock motor, 20G, 9/11.
    Built Motor, L35s, cam.... ?

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    • #17
      Cool, thanks for the info.

      Does datamaster activate both lines??
      Dan
      Factory Five GTM #31

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      • #18
        Originally posted by turbodig
        I built it for a VB app I was writing years ago.
        did you ever get it working?
        Items Wanted
        Exhaust housing & downpipe to fit PTE PT52 turbo | Uncut tail light harness for a Syclone

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        • #19
          Originally posted by canadian
          Originally posted by turbodig
          I built it for a VB app I was writing years ago.
          did you ever get it working?
          Sorta.

          About the time I started working on the UI heavily, DataMaster came out.
          Wasn't much sense in re-inventing the wheel.

          I had a few PC's where I couldn't get it to link... timing specifics.
          I started on some rolling-timing link code, but I never pursued it further.

          I always wanted to implement mode 4, so we could command the ECM
          to do things. Not much utility, but kind of neat, nonetheless.

          Later,

          Dig
          Dig
          11.94@114- 100% stock motor, 20G, 9/11.
          Built Motor, L35s, cam.... ?

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          • #20
            I just modded my cable for this the other day. I simply ran a diode from each pin to where my power wire connected to the resistor. No regulator or anything (since it was running off direct +12V before). Works great on my Compaq LTE5280 (P120, 32MB). My only problem was that on my cable (the prototype), I didn't hook up the "ALDL" ground to the circuit, only the lighter plug ground, so I had to fix that too in order to completely bypass the lighter plug.

            If anyone else wants to mod a cable from me for this, I used 2.5A, 1000V diodes from Radio Shack (276-1114, it's a pack of 3), which are the same rating as what I used in the cable's circuit. Just scrape off the liquid electrical tape where orange wire goes into the resistor, and solder the striped end of the diodes there, and the other ends to pins 4 and 7 (nothing else in those pins). I was able to put them fairly close to the other stuff, so it all still fits inside the shell just fine.

            Syclone 1456 - Broken, bruised, forgotten, sore
            Syclone 0187 - It's not pink! - For Sale
            The truck shudders. It seems to clench up against the brake. A hissing, whirring, hurting tornado of a sound builds under the black hood.

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            • #22
              Re: aldl interface without 12 volts.

              I did made the RS232 interface for interfaceing my from RS232 <-> Chevy 5.7V8 1995 from this page :
              (but with external power supply from cigarette lighter socket)

              http://www.techedge.com.au/vehicle/aldl8192/8192hw.htm

              But when i connect the interface to the PC (not to ALDL just first measure things at the "M" wire which is supposed to go the to DATA line on the ADLD connector vehicle) i measure only around 3.0V at that wire (without starting a datalog software) and when i start e.g. freescan i measure around 2.7V.
              Shouldn't that wire measure only 5.0V or 0.0V (logical 1 and logical 0) i though the max232 only make 5V or 0V to that interfacing pin?
              I do measure 5Volt after the 7805 regulator so that's ok and i measure around 5.0Volt at pin 12 before it reaches the diode.Is anything wrong ?
              Thanks in advance & pardon my bad english (i am dutch)

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