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upgrading my boe-bot from servos to gearheads — Parallax Forums

upgrading my boe-bot from servos to gearheads

LSBLSB Posts: 175
edited 2006-03-24 21:48 in Robotics
All-
I'm looking to improve robot performance by upgrading my boe-bot from servos to gearheads--using the SN754410 to drive them. I notice that interface requires 6 pins (for 2 motors) and I am a bit short. Since direction control requires INA and INB be opposite (High/Low or Low/High) and gearheads shouldn't require break or coast, I'm thinking a chip that ouputs opposite states (low on pin A outputs Low/High on pins B and C, High on pin A outputs High/Low on pind B and C) would save 2 pins. Can someone name (or point to a thread naming) this chip?

Thanks

Post Edited By Moderator (Chris Savage (Parallax)) : 3/20/2006 3:22:59 PM GMT

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-03-20 15:25
    LSB,

    ·· It sounds like you just need a standard Motor Controller.· A few different controllers can be found at the following link.· As a side-note you should use a descriptive subject line for your posts.· I fixed this one for you.

    http://www.parallax.com/html_pages/products/motorcontrol/motor_control.asp

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-03-20 15:36
    LSB -

    May we presume that by "gearheads" you're speaking of stepper motors with gear reduction? There are many different kinds of motors with gearheads on them, that's why I ask.

    A simple inverter (74xx04) will change a HIGH to a LOW or a LOW to a HIGH:

    /code

    I· 1--*
    1·\
    N 2 --|
    *
    0·· \· INA
    A 3---|
    |
    *
    0· ·/ connection
    ·· 4---|
    |
    |
    *
    1 /
    ········ |········ |······· |·······|
    ······· --······· --·······--······--
    ······· V········ V·······V·······V··· <== 4 x 7404 inverters
    ······· |········· |········|······· |
    ········
    |
    |
    |
    0 \··· former
    ···················
    |
    |
    1· \· INB
    ······························
    |
    1··/· connection
    ·······································
    0·/
    code/

    Apologies for the ASCII sketch.

    Regards,

    Bruce Bates

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    <!--StartFragment -->
  • LSBLSB Posts: 175
    edited 2006-03-20 15:48
    Thanks! Yes an inverter is exactly what I'm looking for and, now, hearing the name I laugh--what else would you call it?
    Oh, I'm sorry about not using a subject-- I was so careful to proof everthing before I posted, but completely missed the subject field.
  • Special_KSpecial_K Posts: 162
    edited 2006-03-24 03:03
    Quick question what kind of motors are you using, and what kind of motors would people suggest.
    sorry it's a little off topic.
  • Kenny GardnerKenny Gardner Posts: 169
    edited 2006-03-24 21:48
    what kind of motors would people suggest

    Parallax used to sell the EZ Roller kit, but I don't see it on the site anymore:

    http://www.solutions-cubed.com/solutions cubed/EZR2003.htm

    Note, that is one link, but they have a space between solutions and cubed so the Forum software stops making a link out of it at the space. Just copy and paste the entire line in your Browser's location box.

    The GHM-04 is good because you can attach an encoder to it and it runs off of 7.2Volts

    http://www.lynxmotion.com/Product.aspx?productID=96&CategoryID=11

    Kenny
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