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Re: reverse engineering ECU->Dash communication?

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  • rtstofer
    ... Did you try using the AC scale? If there is any twitching going on, it should show up on the AC scale even if the DC value averages about zero. ... You
    Message 1 of 31 , Jan 23, 2013
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      --- In Electronics_101@yahoogroups.com, Aaron Turner wrote:
      >
      > Ok, I think most everything so far makes sense. Sounds like the Open
      > Workbench Logic board with it's higher capture rate is the way to go then.
      > Guess I'll worry about debugging this protocol once I know what it looks
      > like!
      >
      > One thing I'm not sure of, is the voltage of that signal wire. I'm just
      > assuming it's 3.3-5V since that's most common, but everything else on this
      > bike is 12V. I put a multi-meter on the signal wire and got nothing which
      > I suppose isn't at all surprising since the meter probably isn't fast
      > enough to pick up anything???


      Did you try using the AC scale? If there is any twitching going on, it should show up on the AC scale even if the DC value averages about zero.




      > Other then a scope, are there other ways to
      > tell? I do know the board is running at 3-6V because that's what the LCD
      > chip I needs as power (and there is a power regulator on the board). Or
      > am I worrying about nothing because nobody does 12V signaling anymore?



      You really need to look at the signals with a scope before you get started with a logic analyzer. Who says they don't use 12V any more?



      > (bike was manufactured starting in 2003). Guess I'd have to find a 12V->5V
      > level shifter?
      >



      Messing this up will result in a trashed logic analyzer. I might start with a resistive voltage divider. In fact, I might use some fairly high value resistors to limit the current and then buffer the result with, perhaps, a Schmitt Trigger device. I would certainly think about clamping the input voltage to both 5V and Gnd using Schottky diodes. That way, if the voltage gets out of range, the diodes will clamp but the current will be low. I don't think I would rely on the internal diodes of the logic device.

      In fact, if the data rate was slow enough, I might use an opto-isolator to remove any possibility of the incoming signal trashing the logic analyzer. Another reason for using a scope! How fast is the signalling.

      I remain unconvinced that this is a 1-wire circuit. I suppose the manuf could be using the frame for the other wire but I would still be suspicious until I saw traces on a scope.

      Richard
    • Aaron Turner
      Yep, EcuEditor is pretty awesome. :) Too bad they don t (yet) support the SV650 ECU. Apparently they re almost done and I won t have to run a Power Commander
      Message 31 of 31 , Feb 11, 2013
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        Yep, EcuEditor is pretty awesome. :) Too bad they don't (yet) support
        the SV650 ECU. Apparently they're almost done and I won't have to run
        a Power Commander any more. It didn't occur to me (until just now)
        that it might be able to tell the ECU to ignore the secondary throttle
        position sensor, but that would probably be pretty easy with that
        software.

        FWIW, BRG Racing (who built my motor and is doing the tuning) has used
        the EcuEditor very successfully on other bikes and prefers that to
        other solutions on the market.

        On Mon, Feb 11, 2013 at 9:52 AM, mark hubrich <meistro57@...> wrote:
        > I was just scrolling through and thought i would post this link..
        > http://www.ecueditor.com
        >
        > Probably too late but what the heck anyway ;)
        > On Feb 11, 2013 10:19 AM, "Aaron Turner" <synfinatic@...> wrote:
        >
        >> **
        >>
        >>
        >> So finalized my board design (very first board I've designed btw!) and
        >> just sent it off to OSHPark for fabrication. Unfortunately I ran out
        >> of time for the secondary throttle position emulator and so I ended up
        >> buying a commercial eliminator. Just gives me something to add in
        >> version 2.0 I guess. :)
        >>
        >> Thanks again to everyone who helped answer my questions!
        >>
        >> On Sun, Feb 3, 2013 at 8:54 AM, Aaron Turner synfinatic@...> wrote:
        >> > Just wanted to say thanks to everyone for their advice. Got this
        >> > working perfectly. :) A little challenging trying to talk at 7800
        >> > baud, but was able to hack the software library to add support for it.
        >> > Then everything pretty much fell into place. Thanks again!
        >> >
        >> > --
        >> > Aaron Turner
        >> > http://synfin.net/ Twitter: @synfinatic
        >> > http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
        >> Windows
        >> > Those who would give up essential Liberty, to purchase a little temporary
        >> > Safety, deserve neither Liberty nor Safety.
        >> > -- Benjamin Franklin
        >> > "carpe diem quam minimum credula postero"
        >>
        >> --
        >> Aaron Turner
        >> http://synfin.net/ Twitter: @synfinatic
        >> http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
        >> Windows
        >> Those who would give up essential Liberty, to purchase a little temporary
        >> Safety, deserve neither Liberty nor Safety.
        >> -- Benjamin Franklin
        >> "carpe diem quam minimum credula postero"
        >>
        >> [Non-text portions of this message have been removed]
        >>
        >>
        >>
        >
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
        > ------------------------------------
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        --
        Aaron Turner
        http://synfin.net/ Twitter: @synfinatic
        http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & Windows
        Those who would give up essential Liberty, to purchase a little temporary
        Safety, deserve neither Liberty nor Safety.
        -- Benjamin Franklin
        "carpe diem quam minimum credula postero"
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