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Need Help! — Parallax Forums

Need Help!

jcoloniasjcolonias Posts: 31
edited 2013-12-18 09:37 in General Discussion
I am planning to teach a course using the ActivityBot and I am experiencing a consistent glitch that I cannot resolve.
My ActivityBot was assempled correctly, I performed all the checks correctly.calibrated the ActivityBot correctly. I run all
the PropellerC test programs correctly, but now when I turn the Bot's power on, to position1 after a couple of seconds it starts
rotating to itself, as if it is in "perpetual" loop and I cannot test any program in which the encoders and/or the servomotors
are used. I put a new activity board in, and the same situation occurs. I have checked the encoder cables if they were switched, and all the electrical connections and everything is in order. What is wrong? I am really perplexed. Any ideas will be greatly appreciated.

Thanks, John

Comments

  • Hal AlbachHal Albach Posts: 747
    edited 2013-12-17 13:01
    Switch position 1 does not apply +5 or Vin power to the servo headers, position 2 does that.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-12-17 14:56
    Hal Albach wrote: »
    Switch position 1 does not apply +5 or Vin power to the servo headers, position 2 does that.

    I don't have an Activity Board but I'm pretty sure Hal Albach is correct. There might be enough power being sent through the control line to get the servos to move a little even though there isn't any power on the center pin. (This situation sure seems strange IMO but possible.)

    BTW, "Need Help!" could be the title of about half the threads on the forums. "Problem with ActivityBot servos" would be a more meaningful title to the thread.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2013-12-17 18:55
    If the Activity Bot works the same way as the Boe Board then yes, Hal is correct..
  • jazzedjazzed Posts: 11,803
    edited 2013-12-17 19:47
    Hope your not trying to do this with USB power only.

    Put some fresh Duracell AA batteries in your bot.
  • jcoloniasjcolonias Posts: 31
    edited 2013-12-17 19:53
    Gentlemen,

    Thank you for your comments. I did use fresh batteries with exactly the same results. The instructions for the calibration
    of the ActivityBot state that once the calibration is performed correctly, turning the power switch to position 1 should not
    start the bot. Mine does!

    Thanks again,

    John
  • jazzedjazzed Posts: 11,803
    edited 2013-12-17 20:05
    John,

    The Learn forum is where Andy looks for answering Education support questions.

    Educators are very important to Parallax. I'll mention this thread to Andy as he may have not seen it.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-12-17 20:18
    Just to be clear, it's doing this with two different Activity Boards?

    Do you have a voltmeter to measure the voltage at the servo header with the switch in the 1 position?

    A picture of the wiring is often helpful.
  • Hal AlbachHal Albach Posts: 747
    edited 2013-12-18 08:22
    I agree with Duane, and additionally suggest that you disconnect everything, leaving just a bare Activity board. Then measure both voltages available at the servo headers while in position 1. With nothing but power connected you should not see any voltage until you switch to position 2. If no voltage present begin connecting parts of your circuits, stopping to measure the voltage at the headers in position 1 and keep adding your circuits until you start seeing voltages at the headers. After making a connection and you start seeing voltage at the header you will have found what is shunting power to the header.
  • jcoloniasjcolonias Posts: 31
    edited 2013-12-18 09:37
    Gentlemen,
    Thanks again for your comments. I called technical services, and are sending me another board. I the mean time it will
    Follow you suggestions and do some voltage measurements. Jazzed, thank you. I should have posted this to the Learn
    Forum.

    John
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