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Topic: URGENT Help with a motor (Read 1 time) previous topic - next topic

alainagius

So I am doing this project and part of it was building a home built conveyor, I am practically learning electronics and programming alone and I've been at it for some time, its a slow but steady process.
However unfortunately as stupid as I might seem, when it came to calculating the torque required to move the conveyor, there was a miscalculation and now that I have come to terminate the project, the motor was not strong enough. It has to be finished within a month and I live on a small island without suppliers. I plan on using this motor;

http://www.sparkfun.com/products/10847


But before I spend €50 on express postage, I wanted to ask if anyone can guide me on how to wire this to an Arduino! (drivers? shields? anything!)
I managed to do the circuitry on all my components but unfortunately I am running out of time and I am now BEGGING for help.

I am not being lazy I have tried my best but this unfortunate event has put me in a time pressing situation and I could use all the help I can get.

James C4S

Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

alainagius

The article states that;

"The motor controllers on this shield are designed to run from 4.5V to 25V"

This motor is rated at 3V, however in the comments on the motor page a lot of users state that it is permitted to run a motor up to 20 times the rated voltage so this would run at 12V ok am I right?

Also the shield seems to cover the whole Arduino card, I need another 6 I/O ports for other components, how am I meant to reach the ports?

RuggedCircuits

You are correct, you can run a motor at higher than its rated voltage as long as you do not exceed its rated current. You use PWM (pulse-width modulation) implemented using the analogWrite() function, on pins that support it, to effect a varying duty cycle (ratio of on time to total period) and thus deliver a varying amount of average power.

For example, the motor you have selected is 3V and 2A per phase, which means if you apply 3V continuously each phase of the motor will draw 2A. Now, if you apply 6V and only apply the voltage half of the time (i.e., duty cycle is 50%, or analogWrite(128)) then you will get the same amount of average power. Similarly, 12V and 25% duty cycle.

The Ladyada motor shield reference above is only rated for 0.6A of current, a bit more with heatsinking. Shields like our Rugged Motor Driver are rated for 1.5A continuous, 2.8A peak current -- again, slightly more with heatsinking (or fan cooling). On our motor driver only 4 I/O pins are used, the remaining Arduino I/O pins are available for your use on the header sockets.

--
The Rugged Audio Shield: Line In, Mic In, Headphone Out, microSD socket, potentiometer, play/record WAV files


alainagius

Thanks a lot for that last post Rugged!
What I would also like to know is that since this draws 2A, there is no way of using the motor directly with the arduino, there has to be a motor driver such as the one you linked to me right?

RuggedCircuits

Right, you absolutely need a motor driver for just about any motor you can imagine to hook up to an Arduino (except perhaps for the tiniest pager vibration motors).

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons

alainagius

Ok getting close to understanding now if you would be as kind as to help me understand whether or not I can use this driver board please.

http://www.sparkfun.com/products/10267

Its the current part that I think will not do right? even if I max out the adjustable current to 750mA it just is not enough for the motor then right?

alainagius

http://www.sparkfun.com/products/10735

would this make more sense? I have the first one already but as I mentioned, I dont think its suitable for the job right?

RuggedCircuits

I'd get the bigger motor driver -- no sense in limiting yourself to 750mA/phase if you say your setup is underpowered.

--
The Rugged Circuits Yellowjacket: 802.11 WiFi module with ATmega328P microcontroller, only 1.6" x 1.2", bootloader

alainagius

OK so strictly speaking that motor coupled with that driver board should suit me fine right?

Also, I posted this query in other forums and someone told me to wire a bunch of heavy duty MOSFETs to the outputs, does that make sense? how would that work instead of a driver?

Finally, what is the difference between a driver and a shield?  :s

Thanks alot!

RuggedCircuits

Yes, that should work fine, as long as you have a power source that can supply the needed current to the motor. Both the motor driver and the power source are limiting factors in how much power can get to the motor.

You don't need MOSFET's -- that's what the motor driver is for. Essentially, a motor driver is a set of MOSFET's already pre-packaged in a configuration for driving motors.

A shield is designed to plug in directly to an Arduino and form a "stack". It can be more convenient since the shield derives its power from the Arduino, and signals from the Arduino flow directly to the shield through its connectors. A standalone driver board needs point-to-point wiring from the Arduino to it, including control signals and power for the driver.

A driver can be on a shield or as a standalone board.

--
The Ruggeduino: compatible with Arduino UNO, 24V operation, all I/O's fused and protected

alainagius

Thanks a million, you are single handedly saving my project I cant thank you enough.

So just to clarify (sorry if im being annoying with all the questions but at the moment I cant afford the money or time to be wrong)

What I am going to do is, plug a 12V power supply (although the motor is rated at 3V, 12V is still an acceptable voltage right? Also the power supply will come from a universal adapter which will transform the 230V from the mains to 12V so the current should be a steady supply) to the the driver board and connect the driver board to the arduino (being a driver board it can not stack like a shield but has to be connected via a conductor i.e. wires?)

That way I should have a good voltage and a driver board to regulate the current correct?

RuggedCircuits

Sounds correct, though the devil is in the details. You should note how much current your 12V power supply is capable of providing, however. It would also help to draw a hookup diagram of how you plan to wire everything and post it for review before applying any power.

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The Basic Motor Driver: simple, inexpensive motor driver for 1 stepper motor or 2 DC motors

alainagius

I attached two images, one of the breadboard setup and the other a schematic. The 12V supply is shown as a 12V battery however that is not going to be my supply. Since I'm going to be using an adapter from the mains I'm guessing the current that can be supplied should not be a problem considering house appliances can run on 3/4A no problem

alainagius

Also I could not find the BigEasyDriver as a component, that there is the EasyDriverv4.4, its wired in the same way though I checked.

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