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Topic: Servo and Motor Shield Confusion. (Read 9906 times) previous topic - next topic

SamKirkiles

Hey Guys!

I am very new at Arduino (I just got started yesterday). I have the Uno, Motor Shield r3, and 2 standard Servos that I bought at Radio Shack:





I want to know how to hook the servos up to the motor shield or uno. There are very little tutorials with the depth I would like for some reason.

Thanks!



marco_c

You don't need a motor shield for a servo, but you do need a seperate power supply for the servo as the Uno can't provide enough power for itself and the servo.

Servo will have 3 wires - +V, Gnd and a signal. The signal needs to be pulsed to move the servo, with specific timing. There is a Servo library that does this work for you as part of the Arduino IDE install, and there is information in the Playground on how servos work.

http://arduino.cc/playground/Learning/SingleServoExample
Arduino libraries http://arduinocode.codeplex.com
Parola for Arduino http://parola.codeplex.com

SamKirkiles

Thanks a lot for your help!

I have 2 questions though. What is this and where can I buy it?



And what is the advantage of having the Arduino Duemilanove rather than the Uno?

marco_c

Looks like the bit you highlighted was the plug? No idea where you get one, but I would just poke some wire into the servo socket and use that if you are building a temporary circuit to test your ideas.

The white thing is a breadboard and you can get those in any elecronics store, ebay, etc.

Duemilanove (2009 in Italian) is for this purpose no different to the Uno. I think it is just a 'older' model with a different CPU.
Arduino libraries http://arduinocode.codeplex.com
Parola for Arduino http://parola.codeplex.com

SamKirkiles

Oh :) I was just not sure how to hook it up because at a hobby store, I asked the owner if he thought it would work and he said definetly not ( mabye so I would buy one of his).

Thanks!

SamKirkiles

Sorry for double posting but I got my servo up and running but it only can only rotate 180 degrees. I was planning to use them as wheels. Would I need a whole different kind of servo or could I modify mine?

marco_c

#6
Jun 26, 2012, 03:18 am Last Edit: Jun 26, 2012, 03:43 am by marco_c Reason: 1
Generally standard servos just rotate 180 degrees. I have seen posts where people have modded the servos to do complete turns, so Google could be your friend here.

If you want to run wheels and you already have a motor shield, then why not just use a standard DC motor or a stepper motor? These can be run from the Arduino thru the motor shield. Examples in the Playground.
Arduino libraries http://arduinocode.codeplex.com
Parola for Arduino http://parola.codeplex.com

SamKirkiles

I think that is what I will do. Thanks!

DuaneB

And because in the picture you are not using separate power, please have a look at the two links in my signature for an illustration and solution of the next problem you will have.

Duane B
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

SamKirkiles

How would I connect 2 dc motors? would I need to use the Vin and GND inputs at all?

DuaneB

Its best to use separate power for motors as just like servos.

Duane B
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

anthonyw40

The motor shield is best suited for motors or geared motors that are less than 2A stall each.
It can run 2 motors at one time or one motor bridged for a total of 4A at stall.

I would not use the motor shield for servo drive only.
 
I would also not modify the ones that you have, you can use them for all sorts of cool things like pan and tilt for Sharp IR or Ultrasonic sensors or a gripper... etc.

Instead, get the Parallax continuous rotation servo.   This is a servo made for robotic mobility using servos.
Radio Shack sells them:
http://www.radioshack.com/product/index.jsp?productId=12798725#
or you can get them at Parallax website.

CAP_Cadet

Hi Sam
Check out this Instructable on the Motor Shield. It covers DC Motors, Stepper motors and code.
http://www.instructables.com/id/Arduino-Motor-Shield-Tutorial

Hope this helps you!
________________
Joseph Anand-Maker
joseph@anandfamily.org

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