Pages: [1]   Go Down
Author Topic: servo motors with arduino uno  (Read 1892 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 1
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

So im fairly new at using an arduino, i have had some experience with the coding of it, but little with the hardware.
For a resent project that im doing, i need to control 5 servo motors, i know that it is not possible to power all the motors from the arduino, so i would have to power them from an external power supply, the problem is that im not sure how to do this.  smiley-eek
Logged

Phoenix, Arizona USA
Offline Offline
Faraday Member
**
Karma: 40
Posts: 5600
Where's the beer?
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Basically from your external supply (make sure it's rated between 4.8 VDC and 6 VDC, max, and can supply around 1 amp or more per servo; depending on how many servos you plan to run at any one time, plus other factors, like load level on the servos, will depend on how big your power supply should be; the 1 amp per servo measurement is a fairly liberal one, you might be able to get away with a smaller supply) you'll have two "rails" - a positive voltage rail, and a ground rail. Hook the positive rail to all the positive voltage inputs on the servos (usually the red wire, but check your servo docs first!), hook the ground rail to the ground on the servos (usually the black wire, once again, check your docs), and lastly, each of the servo signal lines (usually a white wire, check docs) will go to a digital I/O pin on the Arduino (check your servo library docs to verify which pins can be used). Finally, hook the ground pin of the Arduino to the ground rail of the servos. Then write your control code.
Logged

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Toronto,Canada
Offline Offline
Newbie
*
Karma: 0
Posts: 30
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

So im fairly new at using an arduino, i have had some experience with the coding of it, but little with the hardware.
For a resent project that im doing, i need to control 5 servo motors, i know that it is not possible to power all the motors from the arduino, so i would have to power them from an external power supply, the problem is that im not sure how to do this.  smiley-eek
You may use expension shield with external power, such as:

http://www.dfrobot.com/index.php?route=product/product&path=35_39&product_id=264
or this:

http://robotxdesigns.ca/2010/11/08/the-robot-builders-shield-v2-kit/

Remember, you must use external power to operate over 2 serovs or motors otherwise they won't working properlly.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 8
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,

I'm new to this servo control thing too.  Based on the great description above I jotted down a little diagram of a simple servo motor control.  I just wanted to check and see if this diagram is accurate and I understood the post above correctly.

My diagram is http://dl.dropbox.com/u/2622595/Servo_control_basics.pdf

Does this look right?
Logged

Phoenix, Arizona USA
Offline Offline
Faraday Member
**
Karma: 40
Posts: 5600
Where's the beer?
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,

I'm new to this servo control thing too.  Based on the great description above I jotted down a little diagram of a simple servo motor control.  I just wanted to check and see if this diagram is accurate and I understood the post above correctly.

My diagram is http://dl.dropbox.com/u/2622595/Servo_control_basics.pdf

Does this look right?

That looks OK to me, but you should specify in the diagram what kind of "AA" cells you are using; normal alkaline cells will be 1.5 VDC per cell, while rechargeables (generally) will be 1.2 VDC per cell. Based on your diagram, I am assuming you are meaning the latter rather than the former, as driving a servo with 7.5 VDC (if using alkalines) may shorten its life (most servos are rated to run on 4.5 - 6.0 VDC).
Logged

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Offline Offline
Newbie
*
Karma: 0
Posts: 8
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

That looks OK to me, but you should specify in the diagram what kind of "AA" cells you are using; normal alkaline cells will be 1.5 VDC per cell, while rechargeables (generally) will be 1.2 VDC per cell. Based on your diagram, I am assuming you are meaning the latter rather than the former, as driving a servo with 7.5 VDC (if using alkalines) may shorten its life (most servos are rated to run on 4.5 - 6.0 VDC).

Just to make sure I'm on the same page I modified the diagram to show what I think is a non-recommended configuration and then one which I think will work.  I figure you really don't need two separate power sources as long as the one you're using has the current (power) to run the servos and the Arduino.  So while the Arduino board's 5V out may not supply the current necessary you can still pull it from the single power source.  Can you verify yay or nay on the attached sketch? 

I know this stuff is pretty elementary but I've been concentrating on computers and not basic electronics for a long time and I'm just getting back into it.  Thanks!

http://dl.dropbox.com/u/2622595/Servo_control_2.pdf
Logged

Pages: [1]   Go Up
Jump to: