Motor problem

AIman

Question -

I have a motor that uses an adapter like the servo's use but instead of a 3 pin adapter it requires a 2 pin. Whats the best way to hook that into the BOE (uses BS2)? My BOE does not have a 2 pin adapter for motors and all 4 servo hook ups are being used for legs.

Should I simply cut the lead off the motor and wire it in or is there a way to use a 2 pin?

Also how do I code for a straight DC motor? A stepper is similar to a servo, but how does a simple DC motor code?

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Gadgetman

To run a 'normal' DC motor you'll need either a strong transistor(or mosfet) or a full H-bridge, depending on whether or not you want it to go both ways.

In fact, why not just read Nuts&volts #23 as it explains everything.



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Don't visit my new website...

AIman

Why create a second circuit if you can run it the same was as a stepper?

Paul Baker

Can you be more specific in you question? Are you referring to something in N&V #23, if so what page/figure?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

AIman

I am not looking at any figure in particular, just thinking that a stepper motor or servo gets pulses of power. Whats does it matter if a DC motor gets pulses or a contsistant supply of power? Shouldn't they work the for power reasons?

Also thinking that a stepper doesn't really need any special circuit. I should be able to plug in my 2 pin jumper and run a motor straight from the BOE with a resistor or two.

PJAllen

You can run a DC-motor using PWM, but the Servo pulses from the BStamp aren't long enough to do this, they're·quite narrow.· You can effect DC motor speed control using PWM, but you need a constant (and fairly low) frequency (rep. rate).

Stepper motors move by actuating coils in succession, not by turning one coil on/off.

** Post Edit·** ·attached pic; constant frequency, variable duty (True PWM)

Post Edited (PJ Allen) : 12/14/2006 3:59:00 PM GMT

Tom Walker

AIman,
Your posts seem to indicate that you don't have a good understanding of how these motor types differ...and thus, how to control them. This is not a bad thing...after all "Stupid is forever...ignorance can be fixed." Several of the Parallax offerings illustrate the important facts about the different motor types..."What's a Microcontroller?" is probably a good start. Even if you don't do the activities in the book, just reading it is a good experience.

And the materialsw are free!

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Truly Understand the Fundamentals and the Path will be so much easier...

AIman

DC motors I know about Steppers I don't.

Paul Baker

Try these two references:

http://www.ams2000.com/pdf/step101.pdf
http://www.cs.uiowa.edu/~jones/step/

BTW I got both of these links from http://en.wikipedia.org/wiki/Stepper_motor. Wikipedia is an excellent first stop to learn about something.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

AIman

Thanks