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Author Topic: help needed  (Read 620 times)

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help needed
« on: November 21, 2010, 10:29:55 PM »
Hello guys, I am working on a project called automatic gantry system for which I need a micro controller to which I can connect 6-7 dc motors with rating of 12VDC. Can you suggest me any micro controller for this project. Is there any controller in the arduino family which I can use??

thank you...

Offline bens

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Re: help needed
« Reply #1 on: November 22, 2010, 01:37:40 AM »
Hello.

You can't drive motors directly from a microcontroller, so the key thing for you to figure out is which motor drivers or motor controllers you want to use.  You can then pick your favorite microcontroller to control the drivers (probably any Arduino would work).  To select an appropriate driver, you will need to know how much power your motors require (the stall current is a useful spec to know, or at least the maximum current your motors will draw in your application).  Pololu has a number of motor controllers that you can connect to a single serial line, which makes them very easy to control from any microcontroller with a UART:

http://www.pololu.com/catalog/category/10

Motor controllers are more expensive than motor drivers, but they offer a lot of advanced functionality (e.g. high-level interfaces, acceleration control, safety controls, support for limit switches, etc) that would be very burdensome to implement yourself on a microcontroller (both in terms of time spent coding and processor usage), especially if you're trying to drive seven motors.  You can save money by going with motor drivers, but they take more I/O lines (as many as 21, 7 of which need to be PWM outputs, for 7 motors) and offer a very low-level interface.

- Ben

Re: help needed
« Reply #2 on: November 22, 2010, 12:03:32 PM »
Thanks Ben for your reply....

Ya, we can't drive motors directly using a micro controller. I am using a motor shield for Arduino controller for one of my project, but I can connect only 4 motors to that shield and also I am not sure whether it will sustain 12VDC.

I went through the link that u've send, the motor controllers listed there can control 1-3 motors, so for 7 motors do I need 2-3 motor controllers????

Sorry this is very basic stuff, but I'll be using my own micro controller for the first time that's why......

Offline bens

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Re: help needed
« Reply #3 on: November 22, 2010, 12:50:27 PM »
I don't think you'll find a single product out there that can control seven motors, so yes, you will need to work with multiple motor controllers.  The Pololu controllers are nice because they are designed to be easily chainable.  Just connect as many as you want to the same serial lines and send the appropriate serial commands.  If you can tell me the stall current of your motors and how you want to use them, I can make some more specific recommendations.

- Ben

Offline Soeren

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Re: help needed
« Reply #4 on: November 22, 2010, 03:02:57 PM »
Hi,

Hello guys, I am working on a project called automatic gantry system for which I need a micro controller to which I can connect 6-7 dc motors with rating of 12VDC. Can you suggest me any micro controller for this project. Is there any controller in the arduino family which I can use??
You can use a properly rated relay (DPDT) and a power MOSFET for each motor as driver (controlled by any controller, with 2 I/O lines per motor, speed and direction) and you should be able to make a rather tight board with all the bits in place.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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