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Does the Javelin have a ghost? — Parallax Forums

Does the Javelin have a ghost?

atekippeatekippe Posts: 15
edited 2005-01-07 15:26 in General Discussion
Ok, this one's got all of us baffled.· We set up serial communications from the PC to the Javelin through the JIDE Port.· We sent a simple ASCII character to the Javelin to perform a logical "or" operation on it to confirm that it was sending back the correct value.· Well, we found out that when you have your rxUart set up for the COM port instead of the JIDE port were the information is coming in on, the Javelin will automatically echo back the same information sent.·· EVEN IF THE POWER TO THE JAVELIN IS OFF!· Why would it do this?· Is it some kind of built in error checking or is the board wired in some weird way?·

atekippe
ISU

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-01-05 21:40
    Yes, it's a hardware ghost. The design of the inverter circuitry causes a hard echo (same as on the BASIC Stamp). Now that you know this, you can filter it with your PC program.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas, TX· USA
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-01-06 15:28
    Note also the JIDE port puts out additional hand-shake bytes to support the IDE debugging. I believe it is possible to filter these bytes, but probably easier to put in a second MAX232 to some other Javelin pin than the IDE port.
  • atekippeatekippe Posts: 15
    edited 2005-01-07 15:23
    Thanks Jon

    atekippe
  • atekippeatekippe Posts: 15
    edited 2005-01-07 15:26
    Sorry, forgot to thank allanlane5·too.· We were wondering about that as well.

    atekippe
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