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  • Topic: Airwire to Xbee Digimesh

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    • December 10, 2018 12:17 PM EST
      • Charlottesville, Virginia
         
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      Airwire to Xbee Digimesh

      I've been messing with some new network thingies to deliver DCC (and other stuff) to my trains and such, thought perhaps some might be interested-

       

      http://martinsant.net/?p=3822

       

       

    • December 10, 2018 3:44 PM EST
      • Be Nice
         
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      OK, to perhaps oversimplify one aspect, you filter out the redundant messages to single ones and then send them via a Zigbee mesh with guaranteed delivery.

       

      This "redundant" message issue is because the AirWire was not using a transport protocol with no acks... in fact really no protocol at all, just the raw DCC commands?

       

      Greg

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    • December 10, 2018 4:25 PM EST
      • Charlottesville, Virginia
         
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      Yes, Airwire just streams out constantly.  Eric demonstrated this with his circuit some time ago.  I'm not sure if I'm using the exact same device as he did but it's a generic cc1101 off of Amazon for $10. I didn't use his code but I pilfered his initialization values for the radio and it came up first time. Nice. It's basically DCC over the air.  You can hook the output of the modem directly into a DCC amp and it will drive a decoder. (you can stop right there if you want a cheap Airwire receiver)  But I take that stream and (de?) construct the DCC data packets (as bytes) on the fly.  I then send them over the Xbee network only if they have changed since the last one.  The exception is if  nothing changes from the Airwire input, I send out the last packet every 100ms or so to keep the watchdog at the destination alive.  Also, technically, this is Digimesh, not Zigbee.  Same principle, mesh, but different implementation (cheaper too).

    • December 10, 2018 11:36 PM EST
      • Port Orchard, Washington
         
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      So does this mean you're one step closer to figuring out the Protothrottle Zigbee langauge, and combining it with your other stuff?

       

      Way over my head, but interesting.

    • December 11, 2018 9:16 AM EST
      • Charlottesville, Virginia
         
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      Craig,  short answer, yes.  The problem with the Protothrottle is well, it's half a grand and I can't quite justify that now.  However, it has one thing going for it, it's all open source so the code is available, I've already converted it to an Atmel Studio project and spent some time looking through it. I don't think it would too hard to convert it to Digimesh.

       

    • December 11, 2018 3:35 PM EST
      • Port Orchard, Washington
         
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      I'm seriously considering buying a Protothrottle and I'm in the process of trying to save my hobby money up to buy one. I have no idea on the coding side, but I'd be willing to work something out with you, so we could make it work. 

    • December 11, 2018 3:46 PM EST
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      • Your Host in Littleton, MA
         
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      The Digimesh looks neat, Im gonna have to play with some.

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    • December 16, 2018 12:27 AM EST
      • Port Orchard, Washington
         
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      Martin,

      Good news, the guys at ISE have a loaner throttle for testing. I Cc'ed you on a email, but wanted to post here as well. 

      Maybe this is what you need to make this thing work.

      Craig

       

    • December 16, 2018 9:21 AM EST
      • Charlottesville, Virginia
         
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      Ok, that's cool.  I emailed them back.  I'm open for any time they can spare it.  Thanks for following up with them.

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