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Question about servo controller (#28023) — Parallax Forums

Question about servo controller (#28023)

ArchiverArchiver Posts: 46,084
edited 2004-07-12 17:40 in General Discussion
Hello again everyone. First of all I will have the website about the
skull I made up soon. I'm interested in hearing suggestions on how
to more efficently do some things...

As far as the servo controller (#28023) is concerned, I've just read
through the documentation, and have a few questions:

When you position a servo with this controller, is it's position
maintained (ie is it continually pulsed until told otherwise?) Or is
it just moved to that position (but not continually pulsed
thereafter)?

It says in the documentation that you need a seperate power source
than for example the BOE board. Is there any way to use the power
from the BOE if using a wall plug power source? (Like using the
jumper on the BOE rev C to set the servo headers to Vin rather than
the 5v setting?

Thanks again,
Ryan

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-07-12 17:28
    The PSC will in fact hold your servo at the last commanded position by
    sending the proper signals every 20 ms or so. You don't need to worry
    about refreshing the servos, that's the job of the PSC. When you want a
    servo to move, send a new position command and the PSC will do
    everything else.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office


    Original Message
    From: LostboY [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ECMviqHRiKiKKR7bd-WrgT8rNtsGnQY4J3IDd_CLGI_CxRM2heNlFe-tdU9sAgRlu0TxW5v6_xS3]hangook21@y...[/url
    Sent: Monday, July 12, 2004 1:08 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Question about servo controller (#28023)


    Hello again everyone. First of all I will have the website about the
    skull I made up soon. I'm interested in hearing suggestions on how
    to more efficently do some things...

    As far as the servo controller (#28023) is concerned, I've just read
    through the documentation, and have a few questions:

    When you position a servo with this controller, is it's position
    maintained (ie is it continually pulsed until told otherwise?) Or is
    it just moved to that position (but not continually pulsed
    thereafter)?

    It says in the documentation that you need a seperate power source
    than for example the BOE board. Is there any way to use the power
    from the BOE if using a wall plug power source? (Like using the
    jumper on the BOE rev C to set the servo headers to Vin rather than
    the 5v setting?

    Thanks again,
    Ryan
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-12 17:30
    That is great news. Thanks for the info (I did read the PDF about the
    PSC, but it didn't mention if it would continue to pulse for me)

    Can you jumper the BOE rev c to the 'input power' for the servo
    headers and use those to power the PSC?

    Ryan


    --- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
    wrote:
    > The PSC will in fact hold your servo at the last commanded position
    by
    > sending the proper signals every 20 ms or so. You don't need to
    worry
    > about refreshing the servos, that's the job of the PSC. When you
    want a
    > servo to move, send a new position command and the PSC will do
    > everything else.
    >
    > -- Jon Williams
    > -- Applications Engineer, Parallax
    > -- Dallas Office
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-12 17:31
    Hello Ryan.

    The following answer is from the developer of the PSC.
    He's not subscribed to the forum, so I'm posting it for him

    Saludos,
    Aristides Alvarez
    Education Manager
    aalvarez@p...
    Parallax, Inc. www.parallax.com
    USA

    Hi Ryan,

    I can answer your questions regarding the Parallax Servo Controller.

    1) The current version of firmware pulses the servo continuously. We

    are working on a version in which you can disable/enable any servo with a
    serial command. I imagine we will release that version at the end of this
    month.

    2) Its possible, though untested. First, you would need a supply that

    can deliver 2-3 amps at a voltage suitable for your servos.

    Ensure the jumper on the BOE is in the VDD position. This jumper

    controls the power supply voltage to the servo controller itself, so we need
    that at 5 VDC. Servo power must be separate (or as separate as possible).
    Then, connect VIN and VSS from the BOE to the servo supply terminals on the
    servo controller. I don't know if this will work or not, but its the best
    chance you have of using the same

    supply for both.

    Honestly, you'd be better off using a 9V battery to supply the BOE, and
    simply connect the wall plug power supply to the terminal for servo power.
    Remember; servos typically require 4.8 to 7.2 volts, so don't over-voltage
    them - they'll smoke pretty quickly if you do.

    John Barrowman

    Engineering

    Parallax, Inc.
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-12 17:33
    Hey, thanks alot!

    Ryan


    --- In basicstamps@yahoogroups.com, "Aristides Alvarez"
    <aristidesparallax@y...> wrote:
    > Hello Ryan.
    >
    > The following answer is from the developer of the PSC.
    > He's not subscribed to the forum, so I'm posting it for him
    >
    > Saludos,
    > Aristides Alvarez
    > Education Manager
    > aalvarez@p...
    > Parallax, Inc. www.parallax.com
    > USA
    >
    > Hi Ryan,
    >
    > I can answer your questions regarding the Parallax Servo Controller.
    >
    > 1) The current version of firmware pulses the servo continuously. We
    >
    > are working on a version in which you can disable/enable any servo
    with a
    > serial command. I imagine we will release that version at the end
    of this
    > month.
    >
    > 2) Its possible, though untested. First, you would need a supply
    that
    >
    > can deliver 2-3 amps at a voltage suitable for your servos.
    >
    > Ensure the jumper on the BOE is in the VDD position. This jumper
    >
    > controls the power supply voltage to the servo controller itself,
    so we need
    > that at 5 VDC. Servo power must be separate (or as separate as
    possible).
    > Then, connect VIN and VSS from the BOE to the servo supply
    terminals on the
    > servo controller. I don't know if this will work or not, but its
    the best
    > chance you have of using the same
    >
    > supply for both.
    >
    > Honestly, you'd be better off using a 9V battery to supply the BOE,
    and
    > simply connect the wall plug power supply to the terminal for servo
    power.
    > Remember; servos typically require 4.8 to 7.2 volts, so don't over-
    voltage
    > them - they'll smoke pretty quickly if you do.
    >
    > John Barrowman
    >
    > Engineering
    >
    > Parallax, Inc.
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-12 17:40
    You *can* do whatever you want, but if you damage your boards by
    deliberately dismissing a documented recommendation you will void your
    warranty. Proceed with caution.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office


    Original Message
    From: LostboY [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=z5Glr-mIGmIF_qe6CwTIIiheC4HTTy6YZ33PCsn73f5eURayj-hlHdDS23GpvfPvnW6cRHSKRubHd4k]hangook21@y...[/url
    Sent: Monday, July 12, 2004 11:31 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: Question about servo controller (#28023)


    That is great news. Thanks for the info (I did read the PDF about the
    PSC, but it didn't mention if it would continue to pulse for me)

    Can you jumper the BOE rev c to the 'input power' for the servo
    headers and use those to power the PSC?

    Ryan


    --- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
    wrote:
    > The PSC will in fact hold your servo at the last commanded position
    by
    > sending the proper signals every 20 ms or so. You don't need to
    worry
    > about refreshing the servos, that's the job of the PSC. When you
    want a
    > servo to move, send a new position command and the PSC will do
    > everything else.
    >
    > -- Jon Williams
    > -- Applications Engineer, Parallax
    > -- Dallas Office




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