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Pulse width for Parallax servo — Parallax Forums

Pulse width for Parallax servo

D FaustD Faust Posts: 608
edited 2007-07-25 01:53 in Robotics
What is the pulse range for a Continuous rotation parallax(Futaba) servo.· Is it the standard 1.0 to 2.0 ms?·I couldn't find it in the documentation. ·Thanks

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D Faust

Comments

  • PARPAR Posts: 285
    edited 2007-07-24 18:31
    D Faust said...
    What is the pulse range for a Continuous rotation parallax(Futaba) servo.· Is it the standard 1.0 to 2.0 ms?·I couldn't find it in the documentation. ·Thanks

    Yes. But most of the effect will be had near the 1.5ms "stop" time.

    Make sure you calibrate the "center" point to coincide with 1.5ms. See the documentation section, http://www.parallax.com/dl/docs/prod/motors/crservo.pdf·:
    "Adjusting the set point for the servo
    "Using a Parallax screwdriver or an (0x40) size Phillips screw driver. Program the BASIC Stamp® microcontroller you are using with one of the following codes or setup your pulse generator to 1.5 ms at 20ms intervals. Once the pulses are generated and the servo is powered and connected. Insert the Phillips side of your screw driver in to the adjustment port. Once inserted you should be able to turn the internal potentiometer to the left and right. You should see the servo change direction also to the left and right. If not make sure you are making contact with the potentiometer. Warning: do not press too hard you may do permanent damage to the servo. To adjust the potentiometer turn to the left/right until the servo stops turning. Be sure to adjust the potentiometer slowly to in sure you do not pass the set point. If you do pass it the servo will change direction."

    PAR
  • D FaustD Faust Posts: 608
    edited 2007-07-24 18:33
    so the range for the pulsout command of a BS2 is 500 to 1000?

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    D Faust
  • allanlane5allanlane5 Posts: 3,815
    edited 2007-07-24 19:29
    Yes, where the "Stop" command is at 750, or 1.5 mSec. This does assume a 'stock' BS2, not a BS2sx or BS2p or some other 'flavor'.

    And actually your question is not correct.· The range of a BS2 'Pulsout' command is 1 to 65535.· The range of a command pulse for the Servo is 500 to 1000.
    ·
  • OSOKOSOK Posts: 35
    edited 2007-07-24 20:52
    How come the robotics text uses from 650 to 850?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-24 21:30
    Because on a continuous rotation servo there usually isn’t any increase in speed outside those ranges due to the way the servo works. Take care.

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    Chris Savage
    Parallax Tech Support
  • D FaustD Faust Posts: 608
    edited 2007-07-25 01:53
    Thanks OSOK and Chris, I was going to ask the same question. That should help for ramping servos.
    Allan, thank you also for pointing that out.

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    D Faust
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